Eh, I'm having trouble accepting your critique of Static Back for various reasons:

-- I won't deny that the floor flattens my thoracic spine for a short period of time, but there are lots of exercises that put your body in a non-natural position for a short time. Examples include Brugger relief pose, sternal positional Swiss ball release, all yoga poses (hehe), pull ups, etc. You would never do any of those for very long. You could analyze the details of any of them and say "well that's not natural" and "it stresses parts of your body". Is that not true for most exercises?

-- I feel my spine elongate when I do static back for 10 mins. I have to make an adjustment part way through as a result.

-- The part about it weakening you if you overuse it is interesting, but Egoscue includes a combination of exercises including the challenging Air Bench.

-- Last, but not least, I've been getting good results regardless of this or that explanation.