Looks like his truck/trailer wasn't placed on the right platforms. For sure the trucks drive axle doesn't weigh 9920 lbs.
Even the bottom scale ticket shows the trailer was on the drive axle platform and trailer platform.
I have had no problems using LT tires on all my rv and non rv trailers ranging in size from 10k-22k gvwr.
Stock yards on sales days around the loading chutes are alway crowded with trucks and trailers trying to get loaded out or even leave after loading.
At times I have to spin my 36' tri axle GN stock trailer on the center axle getting out of a trap. No problems with full load and a good poly carcass or a commercial grade all steel ply carcass tire. 'course all my tires on my trailers have max sidewall pressures for max performance/reliability.