The only style of Aikido that is truly "O'Sensei's Aikido" is the Aikido that O'Sensei taught himself. If you have a time machine, please share, as I'd love to take a class with O'Sensei.
Everything else is "O'Sensei's Aikido" from the perspective of one of his students.
The way I look at it, is if my sensei's lineage can be traced back to O'sensei, that's good enough for me.