Dolphins are more difficult to punish usefully than humans; for one, they're less likely to understand English.

Moving to object-level advice: I agree that not responding to bad comments or posts is generally a good idea. I think that responding to downvote explanation requests is a good idea about half of the time. Unsolicited downvote explanation is typically done to sway bystander opinion as well as inform the poster, and so deserves its own treatment.