Jeff,
The training etc is over, time to put Mr. Nice Guy to bed.
The objective is very plain and every understands it.Now we have to establish what happens when the rules is violated.In a Union situation or any personnel dealing you should have a fixed procedure. 1 verbal and 1 written and you are out or whatever. But unless you put that in place and it is followed you don't have a chance of stopping this or any other abusive behavior.
I don't know if you are Management or Safety but you can't let the inmates run the asylum.It's not a democracy it's an autocracy. At the end of the day somebody has to make decisions good bad or different and they may be an SOB but as long as they are respected then things will get done. Your people are not respecting anybody by continuing to do the damage.