"Let the bad guys win"
Pretty much been the heart of liberal foreign policy for about thirty years now. After all, their definition of "peace" is simply the lack of open conflict, and a murderous tyranny can accomplish that a lot more easily than a democracy can.
The persistent delusion that if we just let the tyrants have some territory, they won't want any more and will leave the rest of us in peace, goes back a lot further than thirty years.
Sometime, take a look at what the other side has been saying.