I would have to agree with Mr. Goldsbury - as I have had the same experiences when it comes to my post-war sensei and atemi: it is always taught. But for those that don't, perhaps it might helpful to point out some historical tendencies that are usually relative to any historiography.
While history is indeed discontinuous, it does tend to act this way slowly and by degrees - as Mr. Goldbury has suggested. It would almost be a historical anomaly if we could look into the lives of so many people and say, "Bam! Here is where it stopped (assuming it did)." So rarely does this kind of discontinuity hold up to actual historical data that when one does take up this position one almost always has to rely upon "extraordinary" events - such as the ones seen in this case: the enlightenment experience of Osensei; the profound trauma of waging and being defeated in WWII; etc.
Even then, these types of historical interpretations simply do not hold up (9 times out of 10) to the slightest bit of research. Which is why on the one hand you got an offered position that atemi was banned following WWII (or at least during the lifetime of Osensei), and the fact that we can find no current shihan that trained during that time (not even K. Tohei, who had his statements entered as evidence supporting the original position) who did not strike as part of their art and training during that time.
Osensei's extraordinary experiences aside, which is where any sincere historian would put them for the time being, we are nevertheless left with the fact that today atemi is not only rarely taught in the art, or poorly taught, we are also facing the fact that striking is seen as some kind of degradation and/or regression of the art itself. So, if I were to advise someone taking on this heavily politicized history, where Aikido' economic niche in the martial arts world is at stake, I would suggest that we are indeed looking at a discontinuity, one that happened by degrees, but one that is attempting to legitimate itself by tracing it's origin to an abrupt moment that can only be crafted via the cult of personality. In other words, we are looking at a shift in practice, but it's a shift that happened much later than the late 40's, only proponents, or agents of this shift, are claiming otherwise in order to address their own sense of investment. Connecting one's current position it to a founder, and putting it further back in time than their own time period, is the oldest way of gaining legitimacy for that position, especially in the martial arts, and particularly in Japan. In all likelihood, as it has been my experience with these types of "truth games," as Foucault calls them, the real discontinuity probably didn't start taking place until Osensei's life had passed or at least until he was well out of the picture of deciding what will make up the Aikido curriculum and why. This take on things, of course, will be shocking for those who have invested in the aforementioned position concerning striking, but to those looking at the historical data, and willing to accept what it says "as is", it will be heard as something obvious and barely worth mentioning.