Just to be clear - you can push or pull Dan (or I assume Mike or Aukuzawa) with their feet shoulder width apart (without 1 foot forward) on any line in any direction and they will not lose balance - meaning their feet will not move regardless of the manner in which you push.
I'm making much better progress doing that, but I find I am stronger with 1 foot forward these days. (I used to not be! I practiced feet shoulder width apart a lot more initially, but I was cheating by bending forward with my knees way too much.)
The line from anus to navel is the traditional weak vector of people's stances. That weakness disappears if you have the kind of internal power and skills we are discussing.
The make the person crush down thing, has nothing to do with a bow - I'm not bending anything. Just moving my mind and assuming that is moving stuff inside that I can't tell. It really doesn't have much to do with the discussion other than to mention that there are really cool other things once you get beyond the structure stuff to some degree.
Your description of delivering force without weight is accurate enough for me. Obviously f=ma still.
My point is that these basic things to our training that we can all do are so different from what normal aikido teaches, that someone from normal aikido trying to make observations and analysis has GOT to be far off of the mark. I'm trying to help you as kindly as I can come to the conclusion that statements like 'Dan uses too much earth ki (or ground ki or whatever)' really is just silly. You and anyone else from normal aikido simple cannot know enough about what we are doing to make such observations and analysis.
Adding your insight - without the experience of what we actually do is counter productive and misleading to the people who want to understand what we are talking about.
Let me tell you, I'm not too thrilled about being an aikido teacher who is not allowed to discuss what I am teachign in my aikido classes in the aikido forums. But, I accept this is not my call, so I go here to a forum called non-aikido. If normal aikido people come in and start giving advice, I kind feel like - okay so where do I get to discuss these things with people who actually do them?
I'm happy to discuss what I am learning and try to help the uninitiated. But it seems like you were not taking the position of being the uninitiated and that is confusing to everyone.
I hope that clarifies my position.