Mary, sorry about your husband's work situation. I know first hand how dramatic all those union workers can be.
If the guy is making threats against your husband, he should make a complaint with the union head if the company isn't doing anything about it. I can't promise it will help tho.
Your husband's stupid coworker (who I assume is different from the guy that is threatening to drop stuff on your husband's head) sounds like an idiot. I hate the ass kissers. My own husband is a union boss...so I've seen quite a few ass kissers. Just know this- bosses always know who the ass kissers are. Their true work ethic eventually shows up and ends up being their downfall. There is nothing worse than a dangerous coworker.