Team Leads*, especially overnight Team Leads, have a lot of pressure on them. They catch crap from 3 main groups - salaried management, customers and employees (aka "associates") - and nothing they do is enough.
If he felt his crew was screwing him over he could have fired or reassigned them. Immature entitled little *expletive deleted*ck didn't/couldn't realize that though. Instead, "gotta make them pay for hurtin' my feelz".
That's my guess on the why. Maybe we'll find out what the real reason was.
*Team Lead = wage grade management. Responsible for just about everything from hiring to firing, training, getting objectives met. They don't have the final say on anything, that's reserved for salaried management. Expected to "pick up the slack" everywhere, while trying to manage 2 to 8 (or more) departments. I've considered, for about 45 seconds, putting in for the position. The few $$ more per hour aren't enough.