I start to doubt what I heard and thought of it...
I agree on CG to ground would be the relevant value when cornering as tire is where bike rotate around.
For the bigger is more stable part.
Part of it is trail value that naturally come with bigger wheelset. But that can be compensate by fork rake, head angle etc.
Part of it is angle of attack on the same size obstracle (rock/road irregularity). Same size of rock or road crack are less effective at changing wheel direction when hitting the wheel with larger diameter AND higher hub height (which change vector of impact force vs center of centrifugal of the wheel.
Part of it, which I now question, Is the center of the hub height and the interaction when the wind catch the wheel. The biggest part of "wind rotate my front wheel" force is around the hub height, where the rim is furthest forward from the hub. By changing the height of that force, is it like a knee-height kick vs low sweep kick?