thanks for taking the time pondering about it.
I think your that maybe it's not viable with an army of bots or at an X amount of SP.
but maybe with one bot. there should be a sweet spot to this attack where it's viable.
the sweet spot needs consider your own SP, the victim's SP, the amount you demand.
all theoretical of course but who knows.
This kind of attack can be thwarted by an "upvote police" where whales or dolphins or whatever band together.
I do think it's needs more thought by those who knows best, the devs. to make sure it's economically not viable or if there is a why to stop it.