Hi Chris,
Yes, your understanding of what I intended is correct.
I see the difficulty that you and airtren might have and I think it stems from my not specifying that the THS and elevator contributions can be calculated separately and then added together (at least up to the point where significant nonlinearity/stall becomes important).
What the theory says is that the whole THS deflected through 10 deg will produce the same lift force as the last 30% of the chord deflected through 15 deg. If you then take the whole surface at 10 deg and deflect the last 30% by another 20 deg say the total lift will be the same as the surface at zero AOA and the controls deflected through 35 deg, although of course that last bit of chord will actually only be deflected 30 deg to freestream.The difference is the lift generated on the fixed bit of THS ahead of the elevators.
You will I'm sure appreciate this is an artifice introduced to allow one to collapse the data onto a single line, but it does give an appreciation of the aerodynamics without the complication of worrying about what angle a particular surface is to whatever reference ...