I think flagging the post for moderator attention is the quickest route. I don't think the moderators can block an individual, but they can close the question and contact the offending account. Also, my belief is that the owner of the answer or the moderator can delete the answer, and if done quickly enough (not in this case, though), the question owner can delete the question and all answers and comments going with it.
Gerhard "Email Me About System Design" Paseman, 2011.06.24