"If my right arm is set in plaster and is immovable which it should be, therefore my right side will be in a turn over my right hip which is also over my right foot."
No, you are ignoring the substantial and mandatory rotation flexibility of the torso. You arm can be moderately fixed to your shoulder line, but a lot has to happen between your shoulders and your hips.
"This means my shoulders stay in line with my hips with no twisting of the spine even with CBM or CBMP."
This fallacy is why so many dancers who subscribe to it are forced to ruin the alignment of figures. Without rotation your torso, you can't pass your partner cleanly, and must instead push her out of your way. Also dancers who do this don't actually use CBMP on the outside partner steps... because CBMP without torso twist is not physiologically possible.
"My body turns as one unit. Now let us go to our videos or DVD's and look. See if there is a twisting of the spine."
If you watch Jonathan here of Victor & Heather that would be an accurate observation - but look at all the trouble they get into. Watch the British masters and you see why torso twist is required for good dancing.