The thing of opposing same sex marriage itself isn't noteworthy. The fact it was widely discussed in the context of Brendan Eich particularly was noteworthy. Obama opposing that has nothing to do with what Brendan Eich is "known for" - Obama is known for plenty of things, lots of which are on his wikipedia page.
They are saying he's famous for it, not that other people did or did not do it, nor are they saying its a good or bad thing that he is famous for it.
The world is an unfair place. Sometimes its hypocritical. Saying that he should not be famous for it has no bearing on whether or not he is actually famous for it.
Lots of people opposed it at the time. That’s pretty much required in order for it to be one of the biggest human rights issues at the time.
Obama, the president of the united states opposed same sex marriage at the time of the donations, as did most americans. I hardly fight it noteworthy considering how widespread it was.