Wouldn't fault the nerdy guy with glasses if he came back another night to find the guy with a bat and had a nice discussion in the parking lot.
Why? WTF? Why are posters in this thread sympathizing with the nerdy guy?
Watch carefully. Everyone is a villain in this drama.
Beard is postured to take his shot. He's clearly first. You can see he even checks over his right shoulder before focusing on his shot to see that he's clear, and the girl behind him isn't in the middle of her own shot. She isn't. Then the girl doesn't respect his space, and lines up her shot, with the drawback for her cue clearly aimed right at him, violating his unofficial pool hall right-o-way. This distracts him, and he sort of nudges her, indicating without speaking, 'Hey, I'm shooting here, figure it out.' Goes right back to his shot, doesn't make a stink about it. After his shot he's so unbothered and disengaged from this he makes some remark with a smile on his face to his friend. He's noticeably surprised later by the commotion he hears coming from behind him when nerdy guy starts running his mouth.
That's because beard's GF felt the need to say something snide to the girl who was rudely inattentive. She escalated it. There was no need for that.
But then fuckwit nerdface comes over, and rather than confronting the male, passive aggressive little bitch that he is, he starts talking shit to the guy's girl, who appears to have simply said something after the girl who went out of turn complained, probably along the lines of, "Shut up, you were being rude, it was his shot."
That's when beard steps in, doesn't take this shit, and overreacts in a spectacular fashion.
An unfortunate symphony of escalation driven by each participant's inconsiderate or disproportionately inappropriate behavior.