I'm not debating when he entered Oomoto, but rather how it changed Aikido from a combat ready art to an art of PACIFISM. Aikibudo,Yoseikan and Yoshikhan did not adhere to this conversion. They kept to the roots of combat, although they have develop there own variations of. But the fundamentals can still be found.
Mochizuki and Shioda were direct students of Ueshiba and know Aikido better than we do. They passed some combat traditions from the roots of Aikibudo that are not respected by some. It's more of a mentality issue than anything.
I can assure you that in the end Mochizuki agreed with all the things he learnt from O'Sensei, including the idea that winning is wrong, hence organised competition is wrong, and we train for peace, but to do this we must prepare for war.
Look at Saito Sensei's Aikido, it is Identical to what you see O'Sensei do in the 30's, both in his books, and in Demonstrations. Hence it is what Mochizuki and Shioda learnt from O'Sensei. Saito Sensei was doing this in front of O'Sensei on the mats in class in Iwama into the 60's, hence, O'Sensei's Aikido changed less than you think!
The main changes made to the teaching methods at the Aikikai were under Kisshomaru and Tohei.