Interesting point, I had never thought about the difference in pivot point in the air and on the ground.
However, who can tell exactly which is the pivot point on the ground? Are we sure it coincides with the gear? The nosewheel is still on the ground, and will exert a force resisting the sideslip imposed by the asymmetry, so the main gear will sideslip as well...
It seems a bit simplistic to say the pivot is the gear on the ground. Maybe it's between the CG and the gear, probably moving while the correction is applied with rudder....