Well, the purpose of the merit system is to make shitposters like that to put in a lot of effort and thought on their posts for them to rank up. Unless they are okay with their current rank and doesn't care much on whether they get merited or not, I guess there is nothing much we can do about it.
What I am trying to implement into campaigns I manage is users must have merits to join. I currently am allowing users without merits to join(partially), but have started paying higher rates to users with merits. Eventually I will make it a requirement to have merits in order to join campaigns I manage. I would also like to go as far as you must earn merits each week to stay in a campaign.
If all managers do something like I mentioned above, then eventually these shit accounts are phased out and not making any money anymore rendering their accounts useless. With the merit system being fairly new, I can't go full fledged merit crazy on everyone yet. Gotta give ppl a little time to earn some.
What you've implemented in your campaign is great and the idea that every participant in your campaign must earn a merit every week is also good. That way, if there will be users who will cheat their way to earn merit and trade with their alts, we could ban those shits for their wrongdoing. We could ban a lot of users if that happens tho.