It's worth noting that the aliens in this episode are actually characters in the X-men comics. Mojo's gimmick as an X-man villain is that (s?)he is an extradimensional TV producer. When a couple of Mojo's slaves (Psylocke and Longshot) end up joining the X-men, Mojo starts exploiting them seeing as the team has huge entertainment value.
A comic has more room for odd stories like that than a serial cartoon does.
I'd just like to point out that, as silly and comic book logic-y as it is, I think it is established at some point that the Hulk doesn't really hurt bystanders in his rampages.
It might not make sense, but it's about as canon as something can be in comic books, so there you go.