You would think that if he did exist, he would probably be able to provide some sort of (even very short) testimony at the hearing.
Like, really, they couldn't think of anything, anything better than this crazy theory?
I'm guessing "grandpa" doesn't actually exist, especially since its evolved that the alleged grandpa isn't even her biological grandfather but the father of her mother's boyfriend and when Valieva's career was on the line this man was nowhere to be found. This was and is a huge story in Russia - I'm sure there's some capability of enlisting private investigator that could track him down if Mama Valieva and the boyfriend separated and the family ghosted them.