> The argument you make just plays in their hand

Who cares? What are they going to do about it?

> Because in your framing leaves open who gets to decide what it means to be democratically legitimized.

That was already the case. Our enemies don't care about the concept of hypocrisy. They aren't waiting for some moral high ground. They are going to do what they want to do regardless.

> You're argument opens the door for unlimited military intervention.

No it doesn't. If it is bad to invade somewhere, we can simply not do that. And we can judge this based on the situation and the consequences.