Back in February, I discussed the issue of Orson Scott Card and under what conditions people (or just me, really) could ethically consume material by a homophobe who has argued that homosexuality is often linked to childhood abuse and trauma; and that any government that supported marriage equality had lost its legitimacy to govern. (You remember, it was the post with a very short decision tree.) Now that the movie version of Ender's Game will soon come out, many other people have weighed in on the issue, from Chuck Wendig (verdict: he loves Ender's Game, but can't conscionably put money in Card's pocket) to Cory Doctorow (verdict: free speech is sacred, and he doesn't understand the difference between a consumer-boycott and a corporate/governmental blacklist).
Now, as we've seen with other things--Chick-fil-A sandwiches for one example--any attempt to punish a business for the political views of its owners/operators can have a backlash in the form of political people who hold the opposite view: if Chick-fil-A suddenly represents anti-gay policies, then anti-gay people will rush to eat chicken. Is that what will happen here--for every person who avoids going to see the movie for political reasons, there might be someone else going to go see it?
But if the goal is to make a big noise and remind people (who are resistant to change) that change has already happened and to remind other people (who feel left out because of their minority or invisible status) that they are not alone, well, then, boycott on. Because boycotts are not just aimed at the target; they--like all protests--are aimed at the audience. This sort of boycott nicely sends a message that there are limits on acceptable speech.
This doesn't mean that OSC isn't free to speak his mind; it only means that he isn't free from the consequences of doing so. Let's be honest: we've always had limits on what speech was acceptable--you can't yell "fire" in a movie theater because it endangers lives. Maybe you can't yell "your gayness is a tragic consequence of your childhood abuse"--since, after all, that also endangers lives.