While many of you commenting on the thread do know about this issue already, there may be other people on arocalypse who don't. I think part of the purpose of Coy's initial post, and this thread in turn, is to try to get ahead of the misinformation to prevent it from spreading more. Yes, it's happening on Tumblr, but at least half of us here are also on Tumblr and I'd imagine that the rest of arocalypse's userbase also contains some Tumblr users who might unwittingly spread misinformation here.
I'd handle it the way you'd handle any other misinformation. If you see it, correct it if you're able. If you've unwittingly spread it? Make a correction. Again, this may be what a lot of people commenting on the thread are already doing.
Being tired of this makes a lot of sense. My suggestion? Don't mention who coined the word. If someone's tired of people telling them that ace people coined the word, spreading misinformation is not going to help that. It's just going to prompt people to come on their posts and tell them the one thing they don't want to hear - that aces were actually the one to coin it. If people just don't mention who coined it, no one is going to mention the ace community. And if for some reason they did make some comment about terms coming from the ace community without prompting, that would be inappropriate (and you'd also be justified in telling them so).