Farmboy is right, its not quite that heavy. Its weight is all in the nose as well, so tongue weight is too high and that is why the pickup is sagging.
Knowing that these GM's are sprung a little light, I'm more inclined to say that guy has a trailer problem, less than a truck issue. If he were to distribute the weight better on the trailer, it would be safer and more controllable, however he would probably blow out the trailer tires (looks to be 4 load range E tires). If he had a gooseneck trailer of the proper length, it would be much safer and possibly even legal!