For many years, my teacher assiduously studied Saito Sensei's books and taught Aiki-ken and jo. In the late 1970s he took a left turn and started practising and teaching the kesagiri style of cutting from the Kashima-shinryu, which he himself learned from Minoru Sekiya. I believe that this was much more helpful for him in understanding the aikido of his teacher (Gozo Shioda) and of Seigo Yamaguchi: it certainly made is body much softer and improved his kuzushi skills. This way of cutting is not obviously "stopped", as I understand the Iwama shomen and yokomen cuts are, even though I have vivid memories of him making strong and clean shomen cuts that made the wooden tsuba on his heavy Kashima bokken rattle.
My understanding is that cutting, as a kind of metaphor for hand/arm movement in taijutsu, is through the partner, rather than into or onto them. I currently teach both shomenuchi and kesagiri (a diagonal cut through uke's torso from shoulder to hip) with bokken, but the kesagiri movement, which ends with the sword tip at ground level, feels much more relevant to the way my aikido is going. In particular, it emphasises the spiral use of the body I am learning from my internal power teacher. And, as I said earlier, ukemi feels very different in the two cases.
I'm not sure how well that answers your question.
Don't know what weapons Shioda had but didn't Yamaguchi came from Kashima-shinryu background? It makes sense (no disrespect intended) that if a teachers taijitsu is shaped by Kashima-shinryu it would be difficult to graft any other weapons system onto a student's taijitsu. This applies both to your teacher and to you.
Metaphor is a super useful tool when tangible feedback is not available and it is great that this particular one advances your practice. I will take a tangible practice (of striking) over metaphor any day.
As I am getting dangerously close to "my martial art is better then your martial art" territory, so i'll step away from all this to ask - why do care what the founder did. I mean, Yamaguchi probably had minimal exposure to the founder as most early post war students in Tokyo and found his own way with taijitsu and weapons.