Don't worry, Joss Whedon hasn't become a Republican. He has, however, become an excellent performer! All in one take - nice monologue, Joss.
It's interesting to see stuff like this and wonder why it is that there are NO cool celebrity types who swing GOP. At all. Victoria Jackson and Rob Schneider and Meat Loaf and Confused Clint Eastwood - this is the cream of the GOP celeb crop. It's at least partially because the GOP has, in the last few decades, declared war on the popular culture in general, and so has completely alienated any interesting culture creators. There are plenty of celebrities who probably like the GOP's fiscal policy, but the homophobia and racism and misogyny embraced by the party makes siding with Romney a terrible publicity choice. You simply don't want to be publically supporting the guy who said this stuff.
I suspect that Romney loses this election (I suspect the GOP party elders don't even want him to win. The next four years, whoever is in charge, will be hard). And I suspect that in 2016 or 2020 we'll see a new GOP that has shed the Tea Party extremists and that embraces equal rights and decency, while aiming for fiscal conservatism. That party will be able to attract celebrities to support it. In the meantime, they have Kid Rock.