It depends really! If the pintle is, then in theory the trailer will "roll" and the towing vehivle will not, thats good. BUT, if it is in and not allowed to rotate, then the weight of the towing vehicle(if significantly higher)than the trailer could stop the trailer from rolling?!
As the driver, you need to make a mini risk assessment each time you tow depending on load & terrain to be traversed.
I hope that made sense, it did to me