I would argue that for a thing to be normal both of you would have to see it at least sometimes, unless OP lives on the moon and you live on mars.

Kenji does it when he's playing with his daughter, he polishes her nails and she polishes his -- I think this explanation would fly even in the most uptight and puritanical of the conservative crowd. I do wonder whether he'd bow to the pressure of being more "professional" if he was still making videos under the seriouseats or ATK banner.

Maybe he would, but he is quite an oddball in more ways than one. Both of his parents were Harvard/MIT professors, he is not silent about his political views (he at one point literally forbade anyone with a Trump hat to come in to his restaurant) so we shouldn't extrapolate from this one singular case one way or the other.

No male artist born after 1960, no. Last concert I went to was Carrie Underwood. Who was wearing nail polish. (I’m not judging just literally was not aware it was a thing.)