I say a big so what.
Even if you manage to prove that Liberals make movies and tv shows, what comes next? Unlike, say, the news pages and every TV news show except those on FoxNews there's no rule that people making TV comedies need to be apolitical. In fact, the only institution in America that's under any obligation to show both sides is news. And that's on its way out. See Fox.
People who build houses can have any kind of politics they want. People who cook for a living can have any kind of politics they want. People who make movies can have any kind of politics they want.
What efforts to prove that liberals run Hollywood or academia or whatever, is about shaming liberals, trying to make liberals ideas and liberal people something to be ashamed of.