Only allow listening (to Moderators), forbid unmute


I am trying to achieve the following scenario:
One or more users start a meeting, and they have talking/moderator rights. Everyone else who joins after a certain point should only be a listener, and should be muted and not be able to unmute.

Is this possible? I am comfortable with fiddling around the code, I just need a pointer in the right direction, because I can’t seem to find anything about this scenario.