DMs are there to ensure the safety of participants, not to interfere with a scene. And any Dungeon Owner who wants to stay in business would make damned sure the DMs did not interfere. I would certainly not go back to a place that acted as you indicate. Nor do any dominants I know frequent such a place.

I've used "dungeons for rent" before. The DMs were all very circumspect. the one in your story is a creep, and I would not tolerate his behaviour!