Re: Locking/pinning as pain submission...
Interesting discussion. Maybe the fault (as so often) lies in the translation. I prefer to think of "working with the natural" as unforced movement. Sure the joint locks eventually but it doesn't have to be through a movement against the joint, joints will always lock at the end of natural range of motion and perhaps that is whats meant by working with rather than against the joint.
P.S. To talk about Ueshiba K. being "soft" is also lost in the translation I think. The last time I received Nikkyo from him (late 1980's) it certainly was not pain-free.