I believe that Inaba sensei has relatively recently decided to use Kashima no Tachi as the name for what he learnt during his 1.5 years with Kunii sensei, and his subsequent studies.
When I asked him why he continued to teach Aikido taijutsu along with kenjutsu, he told me that he finds it is important for developing yawarami (soft body) - which aids kenjutsu. Of course in my experience there are more than a few shihan and senior aikidoka (of a variety of lineages) who don't exactly feel very soft
