That sounds like standard operating procedure for union thugs.
I was cornered and threatened by two union thugs when I was a teen, just one month older than the minimum to work legally. They informed me that I would get hurt if I didn’t join the union, which guaranteed minimum wage in return for nearly half of what I would have earned at that summer job.
I have had an absolute hatred for unions ever since, and I will not hire union members, negotiate with unions, or buy anything with the union label.
It’s always seemed to me that unions are exactly like the folks that they’re “supposed” to be protecting you FROM!