I don't think responding to a personal attack with a personal attack is a sensible way of acting. But the primary responsibility in such circumstances lies with the person who starts it.

Preemptive personal attacks can't be justified on the ground that the person attacked responded in kind, or even over-responded.

Shimrod's initial post was intemporate rhetoric, but it wasn't directed at Teribus or at anyone else on the Mudcat, or indeed at any identified person anywhere. That's what I meant by it being "non-personal".