Resistance, to have any beneficial effect, must be both logical and quantitatively appropriate.
Never mind that uke is open to any number of lethal responses from nage, not moving or being moved becomes an end in itself. As long as nage is limited to the technique being practiced, a sufficiently large or experienced uke will have the advantage of foresight and will usually be able to maintain immovability. This type of behavior is stymies learning and is not permitted on our mat.
My view would be that the key is in this last paragraph. If uke is not resisting in a way that also closes any openings nage might be able to exploit AND creating a new opening which uke can exploit, the resistance is inappropriate and counterproductive for both partners' training.
As one of my instructors notes from time to time, if one begins fencing training with a serious instructor, it is common that the new student is not permitted to free fence against anyone but the instructor for the first six to eighteen months of practice, precisely because the alternative will create inappropriate conditioned responses to nonsensical attacks that interfere with the creation of appropriate conditioned responses to substantive and meaningful attacks. That was certainly my experience when I studied fencing with the late Maestro Charlie Schmitter
at Michigan State University.