I understand that there is a limit on downvoting -- it doesn't cost karma, but it's only possible up to the limit of one's karma, or something like that.
I seem to recall that it is (or was last I heard) limited to 4 times current karma.
If so, a sockpuppet wouldn't have enough karma. It must have been an account with a real presence here, either bingeing on OCD or using an automated script.
The ideal outcome here may be if a PTB banned the offender, pumped Muga's karma back up then removed all traces of this conversation. This is somewhat too close to an instruction manual and primer for saboteurs.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.