But I've always tried to follow the advice that the best way to deal with conflict is to calmly walk away, if possible.

Wow that is quite possibly the worst advice I have ever heard, without exaggeration. Walking away is a 'solution' that will literally never solve the problem. Now there are times when the best strategic move is to not engage, but that is a statement of priorities and/or timing. But never, not once do you solve a problem by ignoring it. Walking away is not a solution. I hope at least that lesson was learned from this tragic accident :(