For some reason, I find it difficult to reason about these problems, and have never acquired a facility of easily seeing them all the way through, so it's hard work for me to follow these discussions. I expect I was not making an error in understanding the problem the way it was intended, and figuring out the details of your way of parsing the problem was not a priority.

why did you never get back to our discussion there as you promised?

It feels emotionally difficult to terminate a technical discussion (where all participants invested nontrivial effort), while postponing it for a short time can be necessary, in which case there is an impulse to signal to others the lack of intention to actually stop the discussion, to signal the temporary nature of the present pause (but then, motivation to continue evaporates or gets revoked on reflection). I'll try to keep in mind that making promises for continuing the discussion is a bad, no good way of communicating this (it happened recently again in a discussion with David Gerard about merits of wiki-managing policies; I edited out the promise in a few hours).

At this point, if you feel that you have a useful piece of knowledge which our discussion failed to communicate, I can only offer you a suggestion to write up your position as a (more self-contained) discussion post.