It is irrelevant if the device was a real Apple device or not.
Giz knew when he first presented it to them that it was NOT his device.
He told them that, he said he tried to find the owner, hence not his.
Even if it was a fake, it was NOT his fake.
Authentic / fake does not come into the matter at all.
All that matters is if it was owned by Hogan or not when he tried to sell it to Giz.
Giz knew it was not his property, yet they still bought it, which is buying stolen goods (fake or real).
Even if by your guesses they were not told that the item was not his, they are still buying stolen goods, ignorance does not get them off the hook. Any reasonable person would question how Hogan could possibly be the owner of such a device.
Beyond the fact that yes, if it was fake then it certainly could have been his fake, i am not trying to 'get them off the hook'. I am simply pointing out the flawed logic in asserting that the fact that they paid Hogan for it proves they knew is was his. That is exactly why the held back part of the payment...because they couldn't have known if it was genuine or some fake that Hogan cobbled together or bought in China. Obviously they felt strongly that it was, but not certain and hence the withheld payment.
Does this get them off the hook? NO! I have said that. I am not arguing that it does. Clear as mud?