Brah, the thing is, it's not that I don't think someone would do that in a combat situation, but pulling out the sidearm would exponentially easier than trying to whip that big ol thing around.
Have you ever done weightlifting? (not bragging here, I'm a stick)
A barbell weighs 45 lbs: ever so slightly less than an empty PTRS
I could not imagine moving a barbell in any direction in any short amount of time, especially holding it by one end; the other end would immediately crash to the floor, and a barbell isn't nearly as long as a PTRS.
Yes PTRS is even longer then a barbell. so weight distribution goes AWAY from you so its easier to manager. Not all the weight is with you.