Yes I saw the Phoenix rush on eBay but to be fair I never saw a single one of them sell to a buyer who I am aware of them running an arcade and planning to put it there. So you're saying you are assuming eBay buyers are arcade operators. CPS2 was probably the most popular arcade hardware ever made? And maybe the most collected by gamers, but I don't have any numbers to back that up.
So are you saying the rule is any arcade game sold on eBay is eligible for MAME? It's not putting them in MAME that is the problem, it's that there is a double standard.