What I don't agree with is that you assume that the different set of rules is that you can be more insulting. I would say that given the lack of ability to adequately convey meaning in this medium, that we lack body language, tone, tempo and other hints as to mood and feeling... that people should be more forgiving of online indiscretions and read posts as if the other person had a heart of gold. Only failing those tests should anything happen, and seeking clarity would seem to be a more intelligent action than just launching into a stream of verbal abuse.
Bastard.