To the extent read-out speed affects DR, it's already reflected in the DR score. Photographers who care about speed can look at a camera's frames per second.
None of the DxO scores cover frames per second. The sports score is something else entirely.
Trying to cram all aspects of sensors performance into a single score is foolish, IMHO. I regard DR as the most meaningful of the three DxO scores. Those who care about other factors can find the best measurements and weightings rather than relying on the single DxO summary.
In any event, we started with the question of whether increasing the number of pixels would hurt performance (all else being equal, including sensor size and efficiency). Are we in agreement that it does not?