OCSP doesn't seem like the right protocol for this. Apple should probably just ship you a list of hashes of revoked certificates once a day, and should do the check locally. (Obviously, the global certificate database is too big to send to every user, but Apple should be able to determine the subset of certificates they trust, and the even smaller subset of those that are revoked or compromised.)

To me, it sounds like they decided to take the quick-and-easy path of reusing an existing protocol for the use case of stopping malware, but it doesn't really fit. The latency, privacy, and availability guarantees of OCSP just don't match with the requirements for "run a local application".