Focus on the post, not the intention behind it. If someone posts a nonsensical question just to get attention, downvote and close the post as "Not a real question", because that is the flaw in the question.
Typically, this kind of problem resolves itself within one or two questions, since a post ban kicks in unless the user gets their act together really quick. You can flag for moderator attention as well if the post warrants it, in which case you should leave a custom description.
Regarding your feature request, I feel if the option were added there would be an insane number of knee-jerk "troll" flags, given how the term has come to apply to almost anyone you don't like on the internet.