As idkfa's resident gay authority (by virtue of time served in these forums, thankyouverymuch), I hereby grant you movie visitation rights free of guilt. Also, you can drink all the Russian vodka you like. You can even watch the olympics if you want. I mean, I don't know who watches the winter olympics, but still.
Here's the thing: I have it on good authority that Lion's Gate employed, in the making of the Ender's Game movie, male hair and makeup artists and female carpenters and lighting techs, so ultimately your ticket purchase is going to support LGBT concerns. In fact, I would guess that the total percentage of your dollar going to LGBT individuals, not to mention straight-identified allies and ardent supporters, far surpasses the amount going into OSC's piggybank.
If I had to support the social agendas of every person involved with the creation of everything I consume, I would probably die, because I couldn't consume anything. Or die from the craziness of researching all their social opinions.
This all of course ignores that, assuming you didn't steal the book, you have already supported Card's craziness in some small way already.
Anyway, you have permission to see it! There are more important things to boycott or worry over than this.