The way he calls Peter Popoff an "astonishingly vile fuck" for his exploitation of down on their luck people is oddly heart-warming.
His laughing at the antenna on the fake iPhone 5. It's one of the few cases when his laughter was entirely natural, it cements his One of Us status.
This extends to pretty any time something makes him break-down into legitimately happy laughter.
Ashens and the Silver Skull exchanging gifts in "Poundland is the Best Thing About Christmas". It's because you keep expecting a subversive punchline but it never happens.
His comments on how disgusting it is that this thing (a POPStation based on the events of 9/11) should exist (heartwarming in a similar way to the Peter Popoff example above).
He seems particularly outraged both at the repeated use of images from the attack on both the packaging and the game (commenting on how it's a picture of people's friends and loved ones dying), and at just how lazy and obvious an attempt to cash in on a major event it is.
His fanboyism taking hold as he discovers an AT-AT commander minifigure in the Lego Advent Calender, especially considering all of the prequel junk he had to put up with to that point.
Stuart:[Takes a bite, then silence] ...oh, my God...[Beat]...it's actually quite nice!
During the September Loot Crate, Stuart finds an Alien action figure.
For the first time in the history of his channel, Stuart digs through an Estonian military ration and finds that not only is the food of surprisingly high quality, he enjoys everything in the ration. Even the porridge, which he was nervous about from the word go. It's quite nice to see the food gods throw him a bone after all the crap he's eaten on his show.