I need to not engage in a direct argument about this with someone who definitely does not need to hear it from me right now so I'm just going to yell about it on tumblr:

If you believe people should only have autonomy when they aren't hurting themselves then you don't really believe people should have autonomy. "When they're hurting others" is a justifiable boundary because your autonomy shouldn't allow you to infringe other people's autonomy, but drawing the line at hurting themselves is essentially saying you should get a greater say over their well-being than they should, which is the complete opposite of autonomy.

I acknowledge the nuance that sometimes people would have a deeper general preference to have their autonomy overridden in specific instances and respecting them may mean helping them with that but you still don't just get to assume that's the case because you want it to be true.