It's against the guidelines. They are very explicit about such things:
Be civil. Don't say things you wouldn't say in a face-to-face conversation. Avoid gratuitous negativity.
When disagreeing, please reply to the argument instead of calling names. E.g. "That is idiotic; 1 + 1 is 2, not 3" can be shortened to "1 + 1 is 2, not 3."
Please don't insinuate that someone hasn't read an article. "Did you even read the article? It mentions that" can be shortened to "The article mentions that."
