Fascinating... and you know this how? Oh yeah, that's what the thief supposedly told Chen that s/he did. Right right right.
But... how
exactly did that conversation go, pray tell?
"Hello Apple... i want to return Gray Powell's missing iPhone which he left at the Gourmet Haus Staudt establishment. This appears to be a beta prototype which only engineering would know about. Can you connect me please?"
Was that how it went? Or how then?
Like this:
"Hello Apple... I have an iPhone, and it is Apple's iPhone, but it doesn't work, and I want to return it, and it is not like the iPhones on your website. Did I buy it from Apple? No, I didn't. Ahem, I found it if you know what I mean."
What's important is what California law thinks about lost items and picking them up. When an item is lost, and you find it, you have two choices: You can ignore the item, or you can pick it up. If you ignore the item, that's fine. Nobody can blame you for anything. You have no duty towards the owner of the item. But at the moment you pick it up, you enter into a duty towards the owner. By picking it up you assumed responsibility of returning it to the owner. You are just as responsible as someone who parks customers' cars, or an airline that accepts a customers' suitcase for transport. You didn't have to enter into that duty. It was your own decision.
Now if you have an iPhone, and you call AppleCare, and you can't convince them that you have an iPhone that belongs to Apple, then obviously you didn't do a very good job at explaining what you have. No problem, you can still very easily perform your duties - that you entered voluntarily by picking up the phone, nobody forced you - by handing over the phone to the police. It doesn't mean Apple will get it back, but it means you have done what you are supposed to do. And if you are lucky, Apple just might pay you a reward because you did your duty (or they might be tight bastards, that's tough), or the police might never find the owner and the phone is yours, totally legally. As an alternative, you can easily put the phone into an envelope, address it to Apple, 1 Infinite Loop, Cupertino, send it by registered mail, and add a note that you expect a check for X dollars to cover your cost, or alternatively they should send the phone back.
If you instead go and sell the phone - even though you had a duty to return it to the owner, which you entered into voluntarily - to Gizmodo, then the law says that by picking up the phone and not returning it to the owner but selling it for $5000, you have committed theft.
Picking up my phone and keeping it is theft, just as if I asked you "could you hold my phone while I tie my shoelaces" and you run away with it. In the first case, you can leave the phone, or pick it up and return it to me. In the second case, you can say "No", or you can say "Yes" and return the phone to me once I'm finished. Anything else is theft.