Nice argument, but I don't buy it. There is very little of a technical nature in Aikido that isn't also present in Daito-ryu, including all the things that he mentioned. I'm still fairly sure that Sokaku Takeda didn't spend much time in China.
Koshi nage is even more common in Judo - did Jigoro Kano spend time in China studying Ba Gua too?
Then there is Donn Dreager's book on Budo and Bujutsu (Vol.2 I think) that speaks about Oshikiuchi, the forerunner of Daito Ryu Aikjujutsu and it's philosophy of Aiki in-yo ho (Harmony of energy based on yin/yang) which came directly from Chinese Taoism.
There's really no agreement on what Oshikiuchi actually was, and there seems to be some strength to the argument that it was a system of formal etiquette. In any case "in-yo" is a common concept in Japan. Yes, it has its roots in China, as do Kanji and many other things Japanese. That doesn't mean that M. Ueshiba studied Ba Gua.