O'Sensei observed Saotome Sensei teaching the morning class for years. He was very happy with Saotome's instruction. I'm sure he observed others also. He was not retired in the way that you are implying. You should know that if you are associated with an Aikido lineage.
Saito Sensei had a number of opinions. Ill take O'Sensei's comments about his own Aikido after the war as the stronger case.
This should start you out: http://www.aikidojournal.com/article?articleID=34
It's a 15 year old argument, at a minimum. Not many people really contest the issue anymore.
That kind of push test is nothing like what Dan is doing - or rather, it's just the very tip of the iceberg.
Morihiro Saito didn't think so. He used to carry the 1938 edition of "Budo" around to prove it. In any case, after the war he was largely retired.