Are you sure Tim Allen didn’t refuse to be affiliated with the perversion pushers?
That's a great point, and I hadn't thought that could be the reason. I just did a search, and this is what The New York Post wrote about it:
Why Disney passed on Tim Allen in ‘Lightyear’: He’s ‘dumber’ not ‘castrated’
I couldn't find anything via a search that suggested Allen had turned the role down, but I'm sure he's happy now that he had no part of it.