I believe once you opt in there is no way to opt out. And I believe coins of any composition, type, etc are off limits for eBay's pmt system. At least for now.
Perhaps open a new eBay account and link it to PayPal?
I had to create a new one, but even with a new account I noticed I don't get any views for my listings. This new MP system is under ACH, it's no longer through paypal. It is such bs. Basically I just neutered myself in a sense. I have wait 2 days for my money to become available then another 2 or 3 days to clear the bank. There is no way to opt out of it, once I did it ended my silver lsitings for violating the terms. I called eBay twice and will not have me opt out of it. It is such bs.