“A doctor told me that what he may be hiding is his legal race.”
That’s worth $1-2 million? Wow! He’s already owned up to his mulatto status, not to mention many unflattering details about his father. He had no control over how his mother listed him and today clearly self-identifies as Black. A case could be made, I suppose, that he feared that he’d lose some of the 92% Black vote he got had he let this news out before the election. But once it was over, what harm would there have been in coming clean? This doesn’t seem like a likely explanation.
It would, however, make the document he presented a fraud.