An normal constructive discussion in chat at some point escalated and became a personal fight. In my opinion we have place for constructive discussions, even if the participants have strongly differing opinions. We can't accept personal fights. I don't care who escalated first or who said what, I think every personal discussion should be stopped, be it in the chat, on meta or in comments.
As a sidenote - that didn't happen in this case but might happen in other cases - don't prove your point by exaggerating posts, comments, edits or votes. Wikipedia has formed that as a rule, and I think we can make it a rule for our site too.