If Admin wants to be involved and also earn 1.5 to 2% from escrow for his efforts (he deserves it). First, He can setup a wordpress site purely for escrow reason which can be linked to this forum. He can easily find many wordpress developers to do that compared to finding developers for XenForo. Second (my preferred choice), he can setup OpenBazaar (
OpenBazaar ) its a free cryto marketplace, built purely for setting up crypto sites/marketplaces. The Admin will not have to invest in developers, but only on hosting. Setup OpenBazaar purely for escrow and link it into this forum.
This option won't involve the Admin at all, these will be mutually decided between buyers and sellers, but this will only benefit the parties involved and not the forum as a whole, as others won't come to know if the seller/buyer are scammers, and it will be just lead to multiple threads of them accusing each other. They can use Bitify (my preferred choice), bitrated, escrowmybits.