I do hold people responsible for the beliefs and actions of the organizations they belong to and contribute money to. I'll use my own family as an example. My family are church-going christians. I told them some time ago that I would not be attending any family events that took place in a catholic church, including weddings, christenings, funerals, etc. I explained to them that aside from thinking I'm an immoral sinner who will burn in hell, the catholic church actively works on political and social levels to promote discrimination against me, their son/brother/nephew.
I also told them that I wished they would consider that when they considered their own participation in such a group. To this they all responded with the argument that they don't support all of the church's teachings and took what they needed from it and ignored the rest. I asked them if, when they put their money in the basket, there was a seperate basket for money that was earmarked to be used only for things other than oppression of gays and women, or if they added a note to only use it for the things they believed in.
If you support an organization, monetarily, by your presence and by not questioning them on those things you find wrong, you must share the responsibility for the wrong they do. It's like saying I belong to the KKK because of their policies on urban renewal; I ignore all that awful lynching stuff.
That said, I understand that people are often unable to seperate the church, as an institution, from the religion itself. They are afraid of following their religious beliefs on their own, outside of the church. So I cut them a tiny bit of slack.
I don't boycott what my family does. And I wouldn't boycott what John Travolta does, unless I knew that he personally was working against gays. I do continue to boycott participation in organized religions. I am looking forward to seeing this movie.
Art has a double face, of expression and illusion.