The smaller size of the crop pixels goes to compensate for other factors and is crucial in any analysis.
The question isn't whether or not you can stack the deck in favor of a smaller format.
Build a larger format sensor with pixels of the same size as the
smaller (sorry for the brain fart!) format, and all of your math is now irrelevant because the pixel pitch is identical.
The question is what role format size plays in image sharpness. You're ignoring that question and instead addressing what role pixel pitch plays in image sharpness. We all know that, all else being equal, a smaller pixel pitch will result in more sharpness. What most of the people here refuse to understand is that, when the pixel pitch is constant, all else being equal, the larger format will result in more sharpness.
Even beyond that, if the pixel pitch is adjusted such that the two formats have the same number of pixels and the larger format has that much of a larger pixel pitch, the larger format still
results in more sharpness.
The only way that the sharper format can compete is with a substantial
increase in sharpness, whether from a far smaller pixel pitch or newer technology (gapless microlenses, etc
) or better optics or something else.
But, once again, as soon as you level the playing field and give the larger format the same pixel pitch and comparable optics and the rest, the larger format once again regains the sharpness edge.