Maybe being groped by the management in this way might change their minds.

Having a union with access to legal expertise is very handy when someone above you in the work hierarchy is misusing their authority. An individual making a fusss is very isolated.

People often think of unions exclusively in terms of pay negotiations and so forth. Providing help and support in cases of harassment of one sort or another, or helping ensure that these don't ever arise, is liable to be a more important benefit of a good union for most people.