Insults are out of line as well, it doesn't mean that you assault someone who's clearly impaired, and whose thoughts are completely unfiltered and erratic. If he was mature, he'd understand that, regardless of how this guy was "bothering" his woman. Like I said, threats is different, but Davis wouldn't simply say "bothering" if it was more than just insults, or possibly advances. His thoughts are just what I said, erratic and unfiltered
With what we know, that's exactly what it was. It doesn't need to get complicated, just stick to what we know, and that's that some idiot was drunk and "bothered" his girlfriend, no need to get into psychological stuff. A guy who's drunk and "bothered" his girlfriend should be brushed off and ignored, there's no reason to risk suspension, bad publicity, etc. just to put a drunken friend in his place
Edit:
If we are talking psychological, though, that's just what it is, it's psychological. The fact that he's immature enough to clean this guy's clock completely trumps normal psychology