Rickenbacker has been able to get away with their eBay tactics b/c no one with a cheap Ric copy is going to spend the time and money to challenge them. If you own a Ric copy, it's absolutely legal for you to sell it and to call it a copy of a Rickenbacker.
If Steinway chooses to pursue this in the marketplace, it's a lot more serious. It's not a question of a copy, it's about being able to describe a real Steinway as being real. A dealer could challenge it but Steinway could cancel a dealership agreement. They can't be allowed to get away with it. If they try, hopefully some state attorney general will intervene, or maybe a lawsuit in a state with a good SLAPP statute.