Why did Ueshiba and Tohei continue to demonstrate being unthrowable....as a laudable skill?
Why were we told to cooperate when they...did not?
It was just a demonstration, like the jo trick and unbendable arm. Something neat that you can show people and have them feel something, where you're showing them everything and nothing all at once.
Ueshiba took ukemi for kids and women, we have vids of that. I have little doubt he took at lot of it and I'm sure Tohei did as well. They were unthrowable when they needed to be and gave what they had to give to help guide people to whatever skill level they were after.
How does one know ones skill level?
Leave your dojo, go meet BJJ and Judo and MMA guys and let them try and throw you. Find big Somoans and tested sport winners.
Then...try experts in the Martial arts. The latter being far easier than the former.
Sure no doubt, but that was never an ideal that was written into aikido, IMO. It is the beauty of the art and its biggest wart all at once.
When does cooperation...as a physical skill...mean people can only function with cooperation in physical interaction? If we change that, what are parameters? When does Ueshiba style testing to develop ki become aikido?
When does the testing become increasingly stressed?
That style testing, IMO, can't happen until you've got a few people with some level of the skills involved and it's basically what Rob described on both sides.