ownership can be taken.
Consider: The only way you will know me being me, is when you can see me and point at me (or in other words you would have had to be there, the second when it began until its 1st release), the 2nd best would be an army of witnesses that you trust
(It is just an example, not claiming any weird)
It is not the only key that requires verification of yourself, I think it will require more valid proof and it will really cost you time if you want to prove that you're satoshi.
Strong proof is a must so we can really say he is satoshi because anyone can claim that they are satoshi and satoshi's identity is very mysterious maybe it contributed a littles success of bitcoins success, and also many claimants that they say they are satoshi some others proofed that they are not and i really think the real satoshi wont reveal himself he wants to remain anonymous just what like hes coin design its anonymous.