You can add rules to the eBay rules, but you cannot make a rule against their rules
Secondly, where does eBay address whether an auction for a religious observance has to be open to all parties?
If a non-jew would win the auction, and they dont want it cancelled, the seller must either provide the goods or services or take the consequence (and that could mean being kicked off the site)
What the seller should have done is make a Pre-approved bidder listing, That means someone has to contact the seller to get eligible to bid, The seller could just ask the persons name and location and then when Christine O’Connor applies, He could just say she isnt eligible without giving a reason)