"Could" is a wrong word when they are absolutely fake. Soul bound tokens by definition can't be traded in markets. And it's not only in theory that you can't transfer it. it's by design trading it would go against the whole concept. This is equivalent of someone selling tokens called house, and people would be asking that surely those are not real houses you can walk in.
yes, i also ask the same thing. if they are actually soulbound tokens as they promise, why they are transferable and sellable??