Because if he were to kill you, it would summon a horrible thing that would punish him, and though I have no issue with that punishment, I would rather not have to sense its presence again.

[There's an undertone of bitter hatred in the words, though if Bodhi is paying particular attention, he may be able to tell there's the tiniest amount of... fear. This thing is deeply unpleasant in many ways, for Kylo Ren.]