Well, not to disagree with you Mica, but I think Rickenbacker might tell you differently. According to them, Fender and Gibson lost their rights as a result of their delay in asserting them. You cannot sell a Univox Stereo Bass even if you don't mention the Rickenbacker name without them shutting down the listing on eBay, CraigsList, or any other public forum that they can locate. It doesn't matter who is selling the item or how long ago it was produced. It is what their lawyers and the courts require that they do in order to preserve their rights. When I asked them if trimming the hook off the headstock would make it salable, they said that it wouldn't because the body shape and other features still match. Maybe they lied?
In reality, it may not matter to Alembic to protect such a shape if the name is not abused, but it seems to be one of those slippery slope arguments to me. The cost of defense may not justify the benefits or protection, though.