Please don't post this sort of evidence-free insinuation to HN. They're against the site guidelines, and have been for years, because they almost never amount to anything, but do have a poisonous effect on the ecosystem as users rile each other up about them.
"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 hn@ycombinator.com and we'll look at the data."