If the cards were legally acquired in the first place, I don't see how they (the shop) have any moral reason not to upgrade the cards however their customers want. It isn't their laws that prevent high memory cards. And the appeal of this is not just limited to sanctions limited countries. The prices for these modified cards are wildly cheaper than any vaguely equivalent card that and video will allow to be sold from an authorized OEM.
Five for one would love to be able to do that sort of upgrade work and offer it in the Continental US.
It is true that they did not entirely specified what happened to the waste boards here. Clearly somebody who is stripping parts is then reassembling cards and selling them on eBay or other places. I hope it is not this shop, but clearly they didn't even try to disclaim that behavior. I'm not saying they didn't disclaim it because they're guilty, it could just have not come up.