dodge guy wrote:
There is a difference between used for work (to and from) and used for business (transporting goods for money). In that case when I bring my work tools home in my X then back to work I should have a DOT number too!
If the truck is not registered to a business then it is personal!
The truck is registered to a name that is registered to own a LLC. He uses that truck for the LLC so he needs numbers. Welcome to the world of commercial trucks.
Whether he was using the truck to go back and forth to work IDK but if he was and he owns "work" then he is profiting from the use of that truck in his company. The GVWR of that truck is over the 10,000# so he needs the numbers, safety equipment, and medical card to operate that truck. I drive a commercial truck for my personal truck also and it don't matter if I'm going to the grocery for food for my table, if I pass a scale house on my way there I have to go through it. 
If his company is an Intrastate company and not an Interstate company then he was in violation to even be in IA from Texas. If all he got was a ticket then he was doing good. The officer could have very well been in his right to hold him on the side of the road or towed to a holding lot until all requirements were met.
Beyond what most people think about LEOs a commercial vehicle officer has the right to pull you over just because he wants to make sure you have everything in order. Every time I've been pulled over in my commercial F350, the first words out of their mouths have been "you have done nothing wrong I just want to do an inspection". One time the officer did that and rolled my passenger side window down far enough to put the little black box on my window to check my tint. He told me to turn my lights on and emergency lights on so he could check them. He went back to his car and checked them from there. LOL!
All the other time have just been routine inspections with a thank you and on their way.