If the finder claims he called Apple and they told him it was not theirs and he has proof of a call from his phone to Apple then the whole thing becomes a he said she said with the burden of proof suddenly falling on Apple if they initailly denied the call happened.
No, that's because the violation of the law and the crime that was committed -- doesn't depend upon Apple being the owner of the lost item.
If Apple says it wasn't theirs and the guy then proceeded to appropriate the property for himself, on the understanding that it did not belong to Apple -- he still committed the very crime for which he is currently being investigated for right now.
It's a lost piece of property. The law says that you cannot sell it. If you do, you have committed a crime. You have to try to get it back to an owner. If someone says that they are not the owner, the guy still has to get it back to whomever the owner is (and he apparently still doesn't know who the owner is at that point in time).
Once he appropriates that piece of lost property for himself, by selling it -- the crime has been committed... (and likewise for the guy who is buying it...).
Apple's ownership or non-ownership doesn't have any bearing in the violation of the law in California.
It is going to be difficult to get a conviction regardless of the statute.
If it goes to jury, you can bet that the defense is going to make Apple the great big brute of a company that purposefully put a couple of little guys in harms way and they manipulated them into breaking the law even when they tried to do the right thing. Then the big company lied to law enforcement to cover up their evil scheme.
It may not be the truth but it will create doubt and the state has the responsibility to prove beyond reasonable degree of doubt.
LEO will trash the computers they got, force the two guys to waste some money on lawyers then the whole thing will get dropped.
When it is over, Gizmodo is going to be heroes in their little community. They guy that sold the phone will spend more than the $5000 bucks he got and Apple will sell millions of phones. The world goes on.