Hard to say what the heck happened there. But at a minimum, AC let the situation and subsequent communications spiral completely out of control. No excuse for that.
If they had a weight & balance issue and were determined to see the freight go regardless, they could have started by asking for volunteers who'd take a later flight (with some remuneration for their inconvenience). That alone might not have solved the problem but would've deescalated/defused what ultimately happened...whatever THAT was.
Hard to tell what happened from that account.