The guy is not as smart as he thinks he is.
1) Tongue weight will vary based on the angle of the trailer. So if the trailer was close to level and then he lowered it 6 inches to get it on teh scale, the number is NOT accurate.
2) The guy also failed basic math. If the tongue weight is ROUGHLY 10% of total weight, and you add 200 lbs of gear evenly distributed, tongue weight would go up 20 lbs, not 200 lbs.
3) Dry weight plus cargo capacity does not equal weight. If the dry weight is 6,000 and the GVRW is 7,000, that just means you need to limit added weight to 1,000 lbs. Some people will add 700 lbs, and some people will add 1,200 lbs. Given that most people will be overweight, taking it to a truck scale is the right way to do it. Other than representing a limit that shouldn't be exceeded, the GVWR means nothing.