I have to doubt this to a certain degree myself. My sensei took ukemi for O'sensei on many occasions and according to him, If you did not give a honest, hard attack, the next time you came at him, O'sensei would really slam you hard. He also said that he wouldn't use you for uke anymore if you didn't give hard attacks. Going by that, I'd say it's safe to say that he'd see an uke throwing themselves for his sake as an insult and he'd slam them or not use them anymore.
I don't use the word "divine" to describe O'sensei's skill, but it went beyond physical training, that much is certain. Maybe not though, maybe he was just darn good at what he did. I've attacked my sensei many times and found myself getting up off the mat and never really knowing what happened to put me there. I could call that divine or I could call it an excellent manifestation of control, timing and focus.