If I'm not wrong, this is not some regular young student, it is his grandson and current doshu, Moriteru Ueshiba sensei.
I guess that is one name we all left out so far, the current Doshu did know his grandfather.
Stories are O Sensei trained up until the end. He died around 47 years ago. That is not that long ago, like Prof Goldsbury said.
There are people like Stanley Pranin who only made it to Japan weeks after O Sensei died, but he has made an in depth study of O Sensei's life and Aikido. There is Okimura Sensei in Delaware who met O Sensei as a young man petitioning to train, but he does not call himself a deshi of O Sensei and says the vast majority of his training was under Kisshomaru Doshu. And then there are people like Bruce Kumar Frantzis who did train with O Sensei and then quit training in Aikido.