The Apple hardware perspective is mostly just a gimmick. The side-channel leaks are a direct result of the ARM IP core (also not Apple proprietary). This is arguably old news, people have been attacking ARM based mobile devices for years now.

It would be far more interesting to see if they could attack the Apple crypto hardware accelerators which AFAIK are hardened against these types of attack (as is the Apple CommonCrypto framework as of IOS 9). Apple seems to have ramped up their side-channel game in recent years.