I don't have a concrete line to be honest and i certainly don't let the username above the post influence my decision, all of us are prone to outbursts and this is a place for us to just say it and be done with it.
It's just that when things get personal and drag other people in the mix, a few posts get moved here to let the originating thread run its intended course and also let the "duelers" continue going at it in here. The basic forum rules still apply (we do have minors on the boards after all).
If i had to make a parallel, i'd say it's like going to a football match where it's permitted for fans of opposing teams to punch each other up, but only as long as both parties agree to it, there are no lethal weapons involved and they don't endanger others who just want to watch the game
There's normal seating and there's a separate mosh-pit area, people enter the pit either voluntary or get moved there if they get rowdy in the normal seating area, some people watch the match, some people get or give a black eye while catching a glimpse or two of the match, but in the end they all go back home having done what they wanted to do
