Center of mass for the pannier is low to the ground, fixed and very small compared to your mass (say 150 lbs to 10 lbs).

Your center mass is high and produces a much longer fulcrum when you use it to control the bike. Your center of mass is NOT fixed. Your mass is large compared to the unbalanced mass of the panniers.


Therefore:
Unbalanced weight in pannier is inconsequential.


Is his science guy one of those "Climate Change Type Science Guys"