Elementary, my dear Zadok....elementary.
I have enormous respect for Roger but Saint experts like John Albanese were also very definitive in saying if you didn't see the date you'd swear it was a 1909 Proof.
I guess the $64,000 question...or rather, the $2,000,000 question is......if we can never conclusively trace the lineage and whether it is a proof or not....should the coin be marketed or sold as such ?
I think Roger says NO, for good/his reasons....others disagree and probably say unless it has been DISPROVEN as a proof, it gets the benefit of the doubt.
That's the debate in a nutshell as I see it.