The issue here is that Nintendo has just offended a movement that has many friends in big business and government. (Especially among judges. Someone pointed out to me that the gay movement, unlike the civil rights movement, really started out from the power pyramid, with judges passing pro-homosexual rulings).
While you’re right that gay content does not sell, it won’t matter. The gay marriage movement will likely use all the political pressure it has at its disposal to force Nintendo into compliance, and if Nintendo holds fast, they will try to punish Nintendo, as they punished Chik-fil-a, Brendan Eich, Mark Jackson, the Benham Brothers, and others. I think Nintendo will be caving in sooner or later, despite the fact that move will cost sales.
In Brown versus Entertainment Merchant Association, the Supreme Court ruled that video games are considered speech and fall under First Amendment protection. First Amendment is essentially the most consistent part of the Constitution that everyone rallies behind. I don’t see any legal action someone can take if they don’t like Nintendo doesn’t put in gay content in their video games.
The great protection video games has is their frivolousness. But in time after other targets have been dealt with, I can see the political devils come for video games.
When has Nintendo ever altered their product’s content due to politics? I can’t think of any time. The removal of that dungeon music in the N64 Zelda game because it might offend Muslims was more of Nintendo just wanting to sell games and steer away from controversy.
Nintendo isn’t a political company. And I hope it stays that way.