When I've sent a laptop to AppleCare, they're very explicit about the possibility that they won't return the same drive, and that you should backup your data. That said, they've never actually taken a drive from me. So Winer's claim that "they take the old drive" isn't well researched.

Beyond that, Winer straight up doesn't know what they do with the drives; it's pure speculation. What he's really saying is that he doesn't trust Apple. If that's the case, he should take it to an independent Authorized Apple Service Provider that he does — it's just that simple. [Edit: not only can you still get AppleCare coverage at independent providers, but you can easily negotiate with a technician to keep your drive. At the place I worked, the drives that customers abandoned we took great pleasure in destroying!]

Further, when Winer says, "If Steve thinks it's confidential, maybe he should take some steps to protect the info?" — is that not exactly what he's doing?