> I think an important difference is if he “owned” and solelt possessed the data, the warrant would be his to fight (or not comply with) in court.

My understanding from the article is that he was, in fact, given 7 days to contest the warrant, and elected not do so because he didn't want to spend money on a lawyer. Which sounds pretty similar to the options he'd have if he had sole possession of the data and the warrant was served directly to him, though of course IANAL.