Why are most of Steeljaw's survivors Decepticons, with only three of them being traditionally Autobots? Simple, Rodimus and crew are likely to not have been the only Autobots to look at their history and decided they are menaces, or otherwise wanted no part in biofuel. It is likely that Wedge and Override were recruited either after their memories started to fragment and the moral issues were lost, and or, more as is hinted with Wheelie, the need to survive outweighed their morality. Meanwhile Decepticons would probably have only disproven of biofuel during better times because of its inefficiency and not because of its moral implications, so getting Decepticons to use it was not going to be hard.
Chances are, even in the final stages of the war, there would have been more than a few Cybertronians entertaining or suggesting the notion of using biofuel as a solution for saving themselves. This would explain why Rodimus claims to have heard it all before in his refusal to join the Survivors in their plans (as he would have nipped those thoughts in the bud back in the day), and his utter contempt with how they actually went through with it.
The need to conserve energy due to both time and using biofuel inevitably forced the compartmentalizing (and deleting) of data. This has resulted in scattered memories, as well as anything not related to survival (such as empathy towards other sentient beings) being given less priority. Coincidentally, this explains why the likes of Steeljaw still firmly see themselves as Decepticons. The decay isn't so pronounced when what they're doing is just a continuation of what they've always done.
The Survivors gravitating towards Fembrance might seem a bit like a case of Contrived Coincidence, as while it might be the largest inhabited settlement for miles, they could just as easily have found some other spot on Donnokt to land. This could partly be explained away by the Visitor/Nitro and the rest of the Survivors retooling their scanning gear to find potential biofuel. It's also likely that the amount of Energon in the area is so vast that those scanners could have detected it anyway. This is hinted at early on by how Nitro's sensors are able to pick up the raw Energon being used by Fembrance's steam cars as well as Rodimus' energy signature, even though they're listed as unknowns. Thus, though they didn't know it yet, something there is worth checking out.
Despite Donnokt’s gratuitous stores of raw Energon, which are enough to power the locals' nascent industrial revolution with ample stock left to spare, why hadn’t it been detected much earlier when the Transformers still had the resources to do so? Either it’s because the constant war kept both sides from paying too much attention to some backwater planet, or more likely as Rodimus surmised when he first arrived there, it may be due to those deposits still germinating, making them relatively harder to detect even with the best equipment the Decepticons have. It’s this, ultimately, that spared the world and its inhabitants from the fate suffered by the rest of the galaxy.
Although the Survivors claim to have 'adapted' to preserve the Cybertronian species, their very actions on Donnokt only prove to Rodimus that the remaining Transformers learned nothing from the past, regardless of whether they know of the Energon deposits on the planet, as the outcome would be the same:
If they never discover the Energon, they would keep harvesting the natives for biofuel. Even if they 'sustainably' keep them like cattle, sooner or later the Survivors would exhaust the supply and will find some other world to claim as 'home', just as they had done numerous times before. Thus, their cruel cycle would continue until there's literally nothing left.
If they do find said Energon, they'd need to reconfigure their bodies in order to actually make use of it...which would involve farming and harvesting Donnokt's natives anyway until they do. Only this time, with the added wrinkle that this would also fuel fantasies of reviving Cybertron, and rekindling old grudges. Thus, the same cruel cycle would continue until there's literally nothing left.
While the aim is to have the comic have the feel of taking place at the end of any iteration of the franchise if you squint, there are a few parts of the franchise that don't fit well in particular. The Beast and the Animated eras, and it makes sense when you think about what both of those are. They are the good endings to Last Bot's bad ending.
With the exception of Moon, who was not the original character choice for the role and was not originally a transformer, and Scylla, who has been depicted in several comics as being a Decepticon, the lack of Beast Wars characters makes sense because in its good ending the war had ended. The Autobots definitively defeated the Decepticons and their entire species upgraded to be more energy efficient. Even the Predacons, the descendants of the Decepticons, changed to be less destructive in their plans on a galactic-level scale, with the odd exception or two. The worst that the continuity ever gets when it comes to a fate is Beast Wars: Uprising, where the fate of the universe was for the Transformers to be limited to a narrow stretch of space and starve, not destroy the universe's capability of supporting life.
Meanwhile in Animated, the great wars have not only been limited to Transformer controlled space for the most part, but also have been over for millennia. The two factions might despise the other, but they have found a (mostly) stable status quo. Ultra Magnus might have the means to restart the war, but he has no desire to. Megatron wants to restart the war, but he lacks the means without obtaining what he doesn't have at the start of the series such as the All Spark or Space Bridge technology. The galaxy is also thriving, showing no signs of complete life form eradication.
Last Bot Standing is where none of this happened. The Autobots and Decepticons never upgraded into more efficient forms. Their war spread out and destroyed everything around them. Their war didn't end until there was little left.
While it's established that the Forever War was so devastating that The Stars Are Going Out from how energy-draining said conflict had become, due to varying light-years chances are some of those lost lights may have vanished more recently than others, with Shib mentioning how they seemed to visibly blink out from the night sky within living memory. Not only does this open up the likelihood that these could have also been done by the Survivors after milking out whole worlds, but that they've done this multiple times before arriving on Donnokt.
This could also lend weight to why, as much as Steeljaw bemoans his Survivors’ desperate plight, they seem to have a very organized (and drawn-out) protocol for farming and extracting biofuel. They’ve had a lot of practice and time to sort it out.
It can likewise explain Rodimus’ stunned reaction after seeing the night sky and hearing Shib’s account. It’s not simply indicative of how long he’d been on standby. It validates his fears that not only are there other Cybertronians still out there draining the galaxy, but that it’s only a matter of time before they do the same to Donnokt.
Just how many members of Steeljaw's group had been fired forward as a scout and missed the intended target or found a dead end with no way to be retrieved? Ghoulish as they are, such a fate is terrible to imagine.
