You're presenting generalised speculation as if what you're saying is certain. It would be nice if you could provide something that would back up your claim, like a similar case with a one-time buyer that proceeded to trial.

A reasonable person would not necessarily know the goods were stolen, even if they had knowledge of the industry. All the buyer would likely need to say is something like "the seller convinced me that this was an early release for select reviewers", and the only way to counter that would be for the prosecution to provide actual evidence proving their knowledge of the theft. "Legitimate channels" is not confined to retail.