There is no list. Each seller can block anyone they want for any reason. This list is only seen by the seller and workers at eBay (maybe). We do know there are forums and it is possible problem bidders are talked about there. But that is it. Sellers can also block bidders that fall within certain programmed criteria.
Actually, there is the possibility that some kind of list of 'bad sellers/buyers' exists somewhere. I collect many things other than pins, and in many of those hobbies, there is maintained a 'do not deal with' list. These people are specifically named and an example of what they did is provided (sometimes it's just a username on the forum, other times it's their eBay names... Usually where ever the problem took place). Generally, it's because of people blatantly ripping someone off vs selling fake/counterfeit items, but the concept is the same. I only have about 100 people on my blocked list, and probably half of them are people I've never even dealt with... But because I know they ripped off other people, I don't want them to have anything to do with my auctions.
People always say there's the potential for 'legal action', but the response is usually 'This person ripped me off (or sold me a fake item). PLEASE, I'd love to see them in court'. To date, nothing like this has ever happened in the groups I'm a part of (and I honestly wish it WOULD happen with the people I've put on those lists...). If someone is engaging in illegal activity, they aren't going to try to press charges against someone for slander... It's a sad thing, really, that there's someone trying to con people in every hobby...
As for this seller putting the OP on a list, if anything, it's possible this seller has multiple eBay IDs, and blocked the bidder on all of them... No harm done there.
Edit:
Interesting find on the eBay forums from July:
Apparently I am on some kind of list among ebay disney pin sellers. Tried to make a bid and said I was blocked. I contacted the seller and they said I am on a list that is being shared among disney pin sellers to protect themselves from bad buyers.
Sounds familiar, and it seems this person has never dealt with this seller before (tho they stated in a later post that the seller has horrible feedback, so it worked to their advantage in the end). I think one of two things might be true:
1- there's a list among scrapper sellers of eBay IDs of people that complain about their activity. If this exists, you WANT to be on this list since they will have blocked you from bidding on their fraudulent auctions.
2- This is the same seller and he just likes telling people this to scare them into thinking they've been punished for returning fake pins... (Although since this poster had never dealt with this seller's ID before, I'd be curious to know where he got the eBay ID... Unless the buyer had returned something to an alternate ID of the seller's)
Sounds like bullying/scare tactics being used by what are essentially criminals...
Edit 2:
And I just found a fairly large list of Good/Bad eBay sellers on another Disney pin forum... So there is definitely at least one list... Hopefully this is maintained by honest sellers trying to oust those selling scrappers, but you never know who might get on the list...