There has been a similar ban in Manchester T3 for some time, but I have never noticed anyone trying to enforce it.
Perhaps the idea is that you, rather than them, are liable if you drop your outsize, overweight suitcase on someone.
I have seen quite a few airports where loaded trolleys are allowed on escalators, but I get the impression that they may have some mechanism that locks the wheels once a certain degree of tilt is reached. The same idea seems to work on the moving ramps in my local Tesco. As airports move ever nearer to the BAA ideal of a shopping mall with nearby runways, we may get the same things installed in the places that BAA are still running.