"Lying" implies intent to deceive. You can't know intent from internet comments, so that's a personal attack, and personal attacks break the site guidelines. When another comment is wrong, it's enough to respectfully supply correct information.

Yes, we warned you 9 months ago, which means we warned you. If you break the site guidelines after we've already warned you, you're a lot more likely to get banned—and you broke them repeatedly and egregiously. This is not a borderline call!

https://news.ycombinator.com/newsguidelines.html