Seems to me that if the guy tried to give it back and Apple wouldn’t take it, the phone was abandoned property. Where’s the theft?
That's not the way the law sees it in California. With the device being left behind, and thus lost to the owner, the finder is responsible to get it back to the owner or turn it in to someone who will get it back to the owner. If you think one person is the owner and find out that they say they are not the owner -- you still have to get it back to the owner (maybe not the one you "thought" was the owner) but you're going to have to get it back to the right one anyway -- or try to...
Now, under the law, if you appropriate the item for yourself, by selling it (as if you have the right to do so, which you don't under the law) -- then you've committed a crime. And in this case it's a felony.
There's the problem ... :-)
You do not address the fact that someone made several attempts to return it without success and the Gizmodo guy did return it.
Also, please cite the statute and case law that supports your position.