My guess is when he signed on for the first Sonic movie he committed to some number of sequels if they ended up being greenlit. Not that I think he hates to be in those movies, but it seems like a professional obligation to not leave them without one of the mainstay actors
To be fair, the trailers show him becoming an ally and dealing with his daddy issues. I can’t imagine them doing much more with the character, so this might end up being a sendoff.
In the games, Eggman has become an ally several times, but he always goes back to his plans of world domination. He wants to rule the world, so he's not going to let anyone destroy it first.
I think people overlook the way his energy has a dark undertone sometimes. There's something in his high energy performances that throws red flags for me, in a mental health emergency kinda way. But I like that in him.
I have a troubled family, and Jim Carrey reminds me of a particular uncle of mine who has severe bipolar and ADHD, among other things. I think most people find his performances funny because they can't imagine being in the room with someone who behaves that way.
Maybe fun? That passage reads to me that he’s at the point of his career where he can pick and choose his work, and will only agree to it if he can goof off doing whatever the fuck he wants.