IMHO, having actually been in the experience many times, it feels less like anticipation (though unconsciously I won't rule that out) and more like Ikeda Sensei establishes a connection (intent and distance) and begins his technique prior to physical contact. I think of it as capturing and leading the mind and subtle initiating and intercepting while entering. Just before you get there, Ikeda Sensei often subtly changes his line.
I can understand things like that happening, but the instances I was talking about were somewhat different than that and had more to do with Uke obviously wanting to please. I also understand how easy that is to do, the psychology involved, etc., and my comment was simply along the lines that, IMO, the best-case reading of what functionally a demonstration is about can be screwed up by some overly-cooperative Uke's distorting the demonstration through friendly over-cooperation. I.e., my comment is directed at the perspective of what should be happening versus how someone else can be perceiving a demonstration when cooperative Uke's are affecting the demonstration. In the demo's I've explained, the basic principles should be fairly obvious and will hopefully save some people some time with the pragmatics.