To be fair, Lhamo Thondup is the slave owner, Dalai Lama is his title.Personally, I am against any government negotiate with any current or formal slave owners
Lhamo Thondup can die, Dalai Lama can't die as long as he continues to reincarnate.
So negotiating with Dalai Lama is quite fine - just wait for him to respawn. Reincarnation expunges all sin.