User blog comment:God of nothing/Shiba clan logic/@comment-8891571-20130429044719/@comment-7658432-20130501000355

Yes, I was the one insisting the point that no one from Gotei 13 even recognized Isshin though I do not agree with the "not knowing the punkass ryoka" thing because they have no visual similarities.

Somebody said that Isshin appeared to Aizen, Gin, Rangiku and the high schoolers after passing through the dangai which aged both of them greatly but I still doubt that they wouldn't even recognize him because Ichigo did age too and yet his friends still recognized him. Also, how would a facial hair gonna mask his appearance?

Then again, Isshin appeared after Gotei 13's asses were handed down to them by Aizen and Aizen mockingly stated that "the wounds are not that deep enabling you to have consciousness so you can watch how I destroy Soul Society" so surely, they would recognize someone of a Captain level fighting Aizen.

As of now, I do not have any conclusion on as how the Gotei 13 was completely ambiguous about his participation or they just simply doesn't care or at least they do, they just don't/didn't show it.