No, we should not. We should live in a world with correct ideas, full stop. Some ideas are stupid, like racism, creationism, or flat-earth models, and don't deserve "balance". What you call "pro-gay" is actually a human rights issue.
Certainly everyone would be all over him if he was promoting racism, right? Or donating to groups to track down and execute people that have committed apostasy? Certainly Stormfront shouldn't be ostracized for having "political views".
Where do you draw the line? Is disliking gay people to the extent of wanting to deny them rights less important than Mozilla's goals?
Edit: I don't mean to imply that people shouldn't be able to hold incorrect (untrue) beliefs - free speech and thought should be strongly defended. But beliefs are obviously invalid and it should be fair to judge and dismiss people stating untrue things. We don't leap to someone's defense when they say the Earth is flat, why should we defend "two sides" for human rights depending on sexual preference?