I saw the reenactment pop up on (I think) !noncredibledefense a few days before commenting here, thought it was a good fit due to the history you mention above.
The “Top of a bald head” belongs to Georgi Alekseyev, who was Grand Chamberlain of the court of the Russian Emperor, in charge of court finances. He was invited to pose for the role, but refused, as he felt it was undignified. Instead, Repin sketched the back of his head while Alekseyev was engaged in looking at an exhibit of prints. When he saw the painting, Alekseyev recognized his head, and was not pleased, but by then the painting was in the imperial collection.
“Artists being kinda dickish in harmless ways” is one of my favorite categories of trivia.