So when Tsuruzo Miyamoto 7th dan corrects an uchi deshi of Hombu Dojo for a mistake in his ukemi with a swift punch to the midsection (something I saw firsthand), whose mind has been taken? Who has been disrupted?
I think that is a bit vague... I mean, how many times did he try to help him correct his ukemi? If that doesn't sink in, occassionally, showing them why taking ukemi that way is wrong is helpful. My instructor commonly showed me why not to do things by lightly throwing an atemi at my face or stomach. Plus, if this reaction was natural for the sensei.... then it can be argued that his mind wasn't taken at all and that he remained in the moment. If it was planned, vicious and done with malice.... then that is a different story. Your interpretation of any of the above statements doesn't neccesarily mean that was how it was, but something to keep in mind.