That's not the comment that got downvoted though. It came later. Wasn't "you made an assumption of intent" supposed to be an explanation of why the initial comment got downvoted?
But it's also a more complicated point than you're giving credit for. That comment directly addresses lack of knowledge and accuses people of negligence, not lying. I do not parse it as an accusation of intent, and given the followup here I don't think izacus sees it as an accusation of intent either: https://news.ycombinator.com/item?id=42669379
But even if it is an accusation of intent the only accusation is deciding to be reckless. Which seems pretty justified to me.
(And there is a flagged comment that I have a big thing to say if you make me, but I'd rather we just ignore that comment as a separate thing.)