"clearly not in violation or whatever rule was indicated"... (or however, it is worded in the jury choice).

Rarely, but sometimes, it is apparent that a series of alerts may be targeted based on subject matter or individual. That's when I might consider indicating a belief that the alert was "sent in bad faith." The implications are that if enough jurors select this, then the DUer who alerted is given a time-out from further alerts for a time period.

Usually, I give benefit-of-the-doubt, though.

how many people on a jury have to hit that before it triggers something, and what does it trigger? does the alerter get suspended or something?

Not permanent unless it continues to be a problem at the decision of admins.

i will hit that if i think it is someone who just wants someone to shut up.
cant see them banning someone for being an alert troll, but i can see it being part of a picture of a troll that brings the ban hammer.

It was because someone alerted on a poster and it in no way deserved an alert. It made absolutely no sense as to why anyone would alert that post. My only guess was that they were trying to stir up mess.