Easy on Chris guys. I'm pretty confident in fact that he is telling the truth, as he had mentioned this incident a long time ago. Even with his distaste for GM, he's not the type of guy who has a data base of GM lies on tap.
My thought is this: That truck had 4wd and the Gov-Lok, which locks in at least three of the four wheels. Lets say bone stock, but if it has a cheap tuner, installed, even better. Guy backs in, hooks up, and pulls forward easy unitl the weight of the boat is on the trailer, and then stops. He then punches it (from a stand still) and shifts the gear shift into "1" in that order. Tow / haul in or out, does not matter in my experience. Torque management limits the amount of power. The driver probably punched it, didn't go anywhere, and never looked at the tach. Probably didn't get past 3000 rpms. This happend on my 2004 on weird occasions, but if the wheels had any momentum, even the slightest roll, TM was never an issue. Only from a dead stop. Tow/haul seemed to have no effect. 2004 and 2005 were the first years of the drive-by-wire and TM and there was all kinds of complaints about them. Most were fixed by a simple software re-flash.
BTW- a F550 with plow drove past our office with an incredible plume of blue-white smoke. I couldn't tell the year, as it was driving sort of away from me. Not trying to bash Ford, but just utterly amazed at the amount of smoke. Like a landfill fire. I hope the guy makes it home OK.