The product of mass and g/s is momentum, not inertia.
If you look at the kinetic energy side of things you will come up with different figures, and after all that is what all the work being done by the engines is to achieve, as well as overcome drag.
The bottom line is that it is a fact. After fatal accident (of a company a/c) in 1992 resulting from a downwind turn at night in 55kts of wind, this very topic was discussed at length. I spoke to very experienced ex ETPS tutor and he confirmed it to be the case. I've witnessed it too.