We all have our own threshold on this stuff. People get to vote how they want. These particular people are paid by me.
If they announce who they support because a question is asked of them, I shrug. If the announce their support, announce they donate lots of money to the opposition and lead fundraisers to embarrass the President, that that steps over the line and I boycott them.
Now, I don't boycott them when it's convenient. I don't boycott them until they are in some film I have decided to see. I boycott them forever, totally, no exceptions.
They are entitled to their opinion and because of their position their opinion might get propagated widely. If that happens because they were asked, fine. If they become activists, then they are doing so with my money and I shut off the spigot.
Ditto, that goes for music, books, etc. too.