I'm a bisexual, in favour of marriage between arbitrary combinations of consenting adults(even if I have no interest in marriage myself),
and I generally care about politics in tech when relevant.
I fail to see the relevance here.
Seems like he was forced out of Mozilla by a bunch of children who can't handle the fact that people have different opinions and perspectives. Even though I disagree with him on this particular issue, he was not the one acting wildly unprofessionally here. A brief look at his resume and the relative success of Brave as a company suggests he's perfectly qualified at his job.
To be clear, I'm not some Brave fanboy. I don't use Brave because it doesn't offer me anything I need that Firefox doesn't.
Brendan Eich's personal views have nothing to do with it.