Part of the problem is that the cited policy is phrased as a nonbinding "deletion policy" (a discussion of cases when moderators might delete posts or comments) and not a "conduct policy" (discussing acceptable use of the site in general). The closest we seem to have to the latter is the "Site Etiquette and Social Norms" section of the FAQ, which does discuss some unacceptable uses of the voting mechanism but does not contemplate that someone might go so far as to use it to intentionally drive users off the site. That may not be a failure of imagination — it may be an avoidance of the "Don't stuff beans up your nose!" problem. Spelling out lots of ways to abuse the system provides a malicious or mischievous user with a list of things to do.

In any event, it's a bad idea to cooperate with a defectbot.