I have no idea about the particular incident in question, but examples of abusive down-voting are mentioned from time to time. The practice of targeting several nodes from a single monk for downvoting would seem to be the most abusive way to cast votes. For example, merlyn apparently recently experienced this.

Update: By a couple of down-votes it has received, I gather that this node is somehow controversial. Let's see, follows Monastery guidelines...properly formatted...tries to be polite and informative...provides links to support assertions. I must therefore conclude that it violates an unwritten rule of the Voting/Experience System, "you never talk about the Voting/Experience System". Either that or I have discovered an undocumented feature of PerlMonks; discussing down-voting begets down-voting.

Update2: Based on a helpful /msg, it is perhaps best to make clear that I am not advocating the (clearly prohibited) "vote bot" solution that merlyn discussed in this node, rather I was using it as an example of an apparent incident of abusive down-voting.