It' more a misuse of privilege, on their part. I suggest you and some of the locals try to create a movement where no one posts in their Self-mod topics. Get as many people on board so that when they create one a duplicate is created that isn't self-moderated - It can be done by quoting their OP even. Then there is still the ability to have the discussion they can choose to join in or not.

This is the only way to avoid such instances. If these options aren't removed to prevent shady sales tactics I don't see it being removed for someone throwing a tantrum and wiping threads. We just have to be creative in how we deal with these unique situations.

Edit: to at least preserve the conversation you can also start archiving their threads.