I can't object to applying tai chi principles to aikido, I ALREADY DO IT.
What I object to is people do not Practice aikido telling how to do aikido.
And if one is going to use these tai chi principles, I really think they should describe their usefulness in how they apply to Aikido technique, not to simply be able to emulate O'Sensei's Performances. If he thought being Unpushable was essential to aikido, he would have taught it to Somebody, doncha think?
Well, that's the point. These aren't taichi principles in aikido. These are internal skills in aikido. And, yes, these internal skills can also be found in some taichi. But, that doesn't mean they are exactly the same. Similar, I think, but not necessarily the same.
You make a point that I was trying to convey to Ledyard sensei. People don't want to listen to outsiders not doing aikido. So let me ask you about Amdur sensei. Would you listen to him about aikido?
And I don't know about Ueshiba. Wasn't there, wasn't around any of his direct students, so I can't answer your question. But I do know that he told Tenryu to try to push him over and that he wouldn't be able to because he(Ueshiba) knew the secret to aiki. Pretty good indication what kind of emphasis he put on internal skills, don't you think?