I tagged the member in question. When there's no rule in place to deal with this sort of shenanigans, one must use the tools available to them to combat it.
What the user is doing sucks and if not discouraged it can lead to a spamfest on the forum and the spammers will not need to put in any effort at all to run an account farm. I however still think this is the wrong tool to combat it and wrong use of the trust system. Any campaign manager that ignores the neutral feedbacks and still pays for those AI generated posts will likely ignore negative feedbacks too and continue to encourage the user.
The trust feedback cannot block all the holes in the forum moderation policies or it starts to lose its own relevance.