There's no brake lockup, but it IS hard on the "assembly". (Kind of like pushing on a tall stack of blocks - they're unstable.) I doubt it would be much of a "tipping" hazard either, the track is pretty wide, and I bet the top half doesn't have that much mass.
I always lock the hitch, both with a padlock in the lever and a lock in the ball receiver.
Hi-Lo 1707T - Tire Minder TPMS on Tow Vehicle and Trailer, 300W Solar Battery Charger, Equal-i-zer WDH, Progressive Dynamics Converter
2014 F150 Platinum 4x4 3.5L EcoBoost SCrew