I’m curious what problems are you having with the new divers? Are they not doing the job, are they causing environmental damage, are you concerned for their safety, are you worried about getting sued?
Is this an organized project with some status and leadership? Is there any liability, and do you have any authority to keep outside divers from simply collecting urchins on their own? Sorry for all the questions, I’m just curious about the nature of the relationship between you and these newer divers.
As an example, when I used to live in TX, there was a spring that needed constant removal of invasive species, and the land was owned by a university. So they had an organized course that anyone who wanted to dive and do maintenance needed to take. That way they evaluated every diver regardless of background or experience. They were able to do this because they had the authority to restrict access to the spring. It actually worked out pretty well. And it sounds somewhat similar in task type, this was all very shallow diving and required decent buoyancy control while working.
I don’t understand the somewhat arbitrary requirement of AOW or number of dives. There are good new divers and bad ones, and there are good experienced divers and bad ones. When I used to DM in the Caribbean, the worst and most dangerous diver I ever guided was an OW instructor. Go figure!