I thought about it further, and decided that I would have moral qualms about it. First, you are insincerely up-voting someone, and they are using this as peer information about their rationality. Second, you are encouraging a person C to down-vote them (person B) if they think person B's comment should just be at 0. But then when you down-vote B, their karma goes to -2, which person C did not intend to do with his vote.

So I think this policy is just adding noise to the system, which is not consistent with the LW norm of wanting a high signal to noise ratio.