One preliminary point: I really don't care about the controversy between Iwama and AIkikai or any Aikido tribe... That must be said because I absolutely won't take side here, I really don't give a flying you know what.
Agree on all that as long as everybody agrees on the fact we are all reasonning on hypothesis... maybe he was the only one around, maybe he was not, everything is in the "maybe" for us... the fact is that he was chosen, what else can we say?
Well, it's not about Tokyo/Iwama, this kind of thing goes around everywhere.
The fact is...this guy got tenth dan, so did that guy over there, the other guy over there got menkyo kaiden, the guy on the other side over there was asked to be the successor, the one over there had this or that kind of special relationship, it goes on and on, all supported by "facts".
It's hard (IMO) to justify an understanding by reference, not even to a third party, but by reference to one's relationship to that third party.
Anyway, I always enjoyed training with Saito in Iwama, FWIW...