I don't think John mcAffe has any more creditability than the imposter Craig wright. Though there could be some people who personally knows satoshi nakamoto like theymos or cobra or some early Bitcoin developers but I highly doubtful satoshi would be in contact with someone like McAfee.
If anyone was aware of the real identity of satoshi, it will not be a big secret by now and the identity would have being exposed a long time back, i am certain that no one knows the real identity of the person behind all this and so is the reason everyone is excited to know when these sort of topics pop up and i will not believe anyone coming out right now without proving that he has the access to the genesis block chain.
I doubt McCaffee knows who it is. Most likely (say 30-40% chance) it is the deceased Dave Kleiman. That would explain why Craig Wright is trying to convince people he is Satoshi. Possibly Craig even knows how to access Satoshi's Bitcoins but hasn't done so yet due because he can't get access until some time in the future or without some extra info he doesn't know etc.
However there are other good candidates, and I wouldn't be surprised if someone who was integral in the first few years knows the identity. I do not think they are likely to have told anyone let alone McAfee.