>>372325565
You can tick mamamad's box in your list of players to exclude them from ever matching with you. The most you'll have to do is turn their volume down once when you see them in the lobby. If the instance is friends+ and they know the id, they can't be prevented from joining, so this is the best solution.

Tonight mamamad was harmless. Nobody got crashed, nothing bad happened. I know that doesn't satisfy everyone who would rather see mamamad gone even if it turns the instance into a battleground of crashers, but getting through an event cleanly was the top priority and it worked.