User blog comment:Salubri/Final Fight: Reflections of an Unrealistic and Ridiculous Battle/@comment-1272757-20100211220510

Yes, that is a reasonable assumption, but because of Kyoka Suigetsu's effectiveness, we don't know when it was in effect and was not. For now, all we can do is put them in the "unknown" category: we don't know for sure if they were affected, or were not. We also can't throw out the possibility that one of these people's zanpakuto's may be able to counter Aizen's hypnosis. After all, we have yet to see Kisuke and Yamamoto's bankais, and we have yet to see Yoruichi even use a zanpakuto, much less her shikai and bankai. The same goes for Isshin, as we have yet to see any of his zanpakuto's abilities. Another factor that came to my mind would be Uryu's father, who is a Quincy, and is certain to have never seen Aizen's shikai.

That is true I guess. However, Ichigo knows that Aizen, Gin, and Tosen were shinigami, but also traitors, so he may have assumed that Momo was a traitor as well. Until we get an explaination, we may never know.