I agree, you did the right thing. These people are too ignorant to understand that fuel mileage in other vehicles is worse than an H3. They are also too ignorant to understand that threatening someone in this day and age, could end up with them having to fight for their life, or have small pieces of lead removed from parts of their body.
I have traveled through Durango in the H3 and didn't seem to have problems, and I have driven through it a few times in a Jeep. The Jeep actually obtained less mileage than my H3. (Of course, my H3 has an overdrive gear, I guess not all of them do.)
Good luck with the truck.