Turns out, you can't mention that things might be astroturfing on HN because that's against the rules. So _pointing out_ something fishy is against the rules here. That seems very strange to me.
"In comments... Please don't post insinuations about astroturfing, shilling, brigading, foreign agents and the like. It degrades discussion and is usually mistaken. If you're worried about abuse, email us and we'll look at the data. "
It's not that you can't make a post discussing astroturfing on HN or that you can't point out astroturfing to someone that can actually do something about it it's that you aren't supposed to just respond to an article that you think it's astroturfing as that helps nobody even if it is or isn't actually astroturfing.