Another action to consider is to "censure", turn the post into a "hidden message". Sorry, I don't know how that is done. I just know that I see that sometimes in other forums. That is kind of like making them sit in a corner for a while. A warning. Then outright banning when the warnings fail.
Sometimes, people can't express themselves very well through the written word. Sometimes they are just mean; or have had bad experiences with the subject.