My sensei was also a student of O'Sensei and he also said that O'Sensei had said you should only start ki no nagare when you are third dan. You have to have solid technique as there is no point in trying to run before you can even walk.
So you should just allow your uke to take a firm grip on you and then practice technique statically for ten years
before even starting to enter before contact or flow with an attack?
Interesting. Not a bad idea, but you are not going to be attracting a lot of new students over the age of 40, and the smaller, less muscular people are going to immediately sign up at the BJJ place across the street.