Going from "I bet" (i.e., you imagine) something about somebody to making factual-sounding claims ("Dan's words") using that person's name is a big breach of civility and you can't do it here.
You went even further than that and hounded this guy elsewhere in the thread. That's unacceptable on HN, so we've banned this account.
It's a shame u238ed chose to make unsubstantiated allegations against Dan, but he/she does have some valid points. A lot of the article itself is unsubstantiated, and doesn't really give much detail about the actual problems at reddit. It seems to be talking mostly about problems with trolls on subreddits, but that doesn't really have anything to do with toxic workplace. The only somewhat concrete allegation is the sexual harassment at the work parties, but I'm not quite sure how that translates into people of colour leaving.
It sounds like u238ed worked or works at reddit, so presumably he/she has some insight into the culture there.