He's an idiot. Drunk wrestler thought they were "working." He had a right to be offended when he took a beer can across his head -- then and there. Whoop his ass then and it is what is, mistake or not. To shake his hand, claim it's over, and then beat him unconscious half an hour later is clown behavior.
The promoter is a moron, too. If he's not a wrestler and just nearly had a physical altercation with one of your guys, the process of minimizing the potential for more conflict -- common sense concept, really -- should tell you that sending him into the ring to "attack" the same man he nearly came to blows with half an hour earlier is a stupid idea.
Everyone involved is a moron.