A couple more thoughts:
Morihei Ueshiba was relatively untouched by the war - he retired to Iwama in 1942 and lived out the war and most of its aftermath in seclusion. The folks in the countryside weren't even really affected by the food shortages and rationing of post-war Japan.
By the time he emerged he was no longer directing the day-to-day affairs of Aikido, which were left to Kisshomaru.
One huge effect of the war was that it erased the generation of students from the Kobukan. Aikido essentially started over with an entirely new group of beginners after the war. The senior people from the Kobukan either went out on their own, stopped training, or died. Rinjiro Shirata being one of the few exceptions.
Things might have been quite different if that generation had continued to train and develop.
A bit off topic, but didn't Tomiki teach at Tokyo hombu after the war for a short time? Didn't Shioda also stop back? Or was Shioda just visiting Iwama? Shirata ... being an exception has reasons.
On topic ... I was in Saudi during the first Gulf War. Saw zero action except for dodging Scud missiles (and yeah, they came close. We picked up debris from them, felt the ground shake when the pieces finally landed). So, my aikido remained unchanged from that war, spiritually or martially. But, as I said, I saw zero action. Ueshiba in foxholes killing up close is a very, very different experience.