You can't break the site guidelines like this, regardless of how wrong someone is or you feel they are, or how provocative their comments. Please review https://news.ycombinator.com/newsguidelines.html and stick to the rules. I had to warn you about this just a couple days ago. Your good comments are good, but bad comments do more damage. Please take care of this.
Should I just flag posts when people are pushing misinformation? It feels wrong to call in an authority to delete their post instead of dealing with it directly, but it seems like directly confronting people leads to the above.
Appreciated! Well, it's always possible to correct bad information by respectfully providing good information, without breaking the site guidelines. That's what other users are doing (some of them at least!). I'd say flagging is best reserved for when the comment you're flagging has broken the site guidelines itself (which was the case here, but isn't always).