It's not up to you to "talk to flint" OP prison is a "pvp server" which means scams are allowed, however they take form. It isn't up to you to decide which forms of scams are allowed. If he wants to tell people that selling for a higher price is bannable, that is ok. If he says his shop is the highest allowed price point, that is also ok. It's not up to you to decide which "scams" you allow.
Although, to be fair, I hate scammers and always call them out on their BS. This also has nothing to do with disallowed scams such as portal trapping.