In an interview with Variety, Keaton explained why the rumors kept changing as to whether or not he was cast (shifting schedules) and revealed he doesn’t think his villain is necessarily a villain.
Variety: I do think though, in all your roles, you bring an inherent likability, whether you want to or not. It’s been a while since you played a truly villainous role.
Keaton: Yeah, Vulture, recently. But not to give too much away, but interestingly, he is and he isn’t, that character. He’s a really interesting — and more interesting than I thought — villain because there’s parts of him that you go, “You know what? I might see his point.” Really, really. It makes it interesting to play.
Variety: Was there any hesitation, because you had done Batman, going back into the superhero universe?
Keaton: No, I mean, not at all. It’s just a thing. A gig. I don’t mean it’s just a gig, it’s the next job. And you think you can do it or want to do it and in fact I said no, because I couldn’t, it didn’t work in my schedule. Then I’m glad to say, they kind of shifted the scheduling and it worked out. So it fit in and I’m glad I did it.
Michael Keaton has turned down many famous roles, including foregoing a $15 million paycheck for Batman Forever because — in his words — it “sucked,” so getting him to play Vulture apparently took some schedule shuffling on Marvel’s part. You’d think Keaton — post-Batman and Birdman — would have accepted it just to play yet another winged character.