Sounds like the standard liberal tactic being used from anyone from Hilary Clinton; Nancy Pelosi; Barack Obama to people like Jesse Jackson and now Apple. They don't want to answer questions from an audience probably smarter than most of their engineers at Apple, but they snidely want to introduce the hackers to their Security Experts. I'm syre they see right through that BS and Apple probably pissed off the wrong people with this one.
I can find no other primary source that says that Apple was intending to officially attend the Black Hat conference. To criticize Apple for supposed restrictions on a undocumented appearance that was not touted by the promoters in all of their promotion materials is absurd. I think the supposed appearance is bogus.
As I mentioned, this "cancellation" was reported last week and at that time involved only Edge. Not Apple.
Participants in the Black Hat conference have been known to lie about Apple before. Since Apple's non-participation fits much more the history of the company and its known reticence about talking about anything security related, I strongly doubt that Apple's security experts would have scheduled themselves to be featured at a conference with the animosity that it has shown in the past toward anything Apple. Blue, it makes no sense.