Is it fair for comments to be disabled, to begin with?
Fairness is about reciprocity.
My longstanding policy is to ignore such answers rather than downvote them; then again, I don’t downvote anyone unless the answer is misleading or offensive. But I sympathise with those like Frank Dauenhauer who do.
Note also that, given how blunt Quora’s UI is, the true meaning of upvote and downvote is not “this is an objectively good answer” and “this is an objectively bad answer”. It is “this is an answer that I want to see more of” and “this is an answer I want to see less of”.
(I tried to find chapter and verse in Laura Hale’s writings to back this up, because that’s what I recall her saying, and I can’t. Laura, feel free to chime in. And hey, aren’t you meant to be in town?)