Not obvious that the manager was about to assault.
The cup was a projectile - could have been filled with heavy ice, etc. That was an assault.
Picking up the chair and advancing towards the manager is another assault that the manager handled well - and actually showed a measure of de-escalation.
If the Owners toss the manager this will serve to encourage stupid customers and further bad behavior.
“Not obvious that the manager was about to assault.”
Was to me. She was aggressively moving quickly towards the customer.
Don’t piss on our legs and try to tell us it is raining.
No judge accepts such movements as friendly.