Why would anyone expect a tire that was specifically designed to be use for trailer service; straight running, a non-steering axle, straight running tread design, stiff sidewall and service below 65 mph expect it to be suitable for two vehicle service?
Still, there are fools out there that will ignore the intended purpose of the tire then sue the company because it did not work right. Hence the required warning.
Tires are marked in many way, my riding lawn mower tires say "not for highway use" to keep some nimrod from putting them on a boat trailer.
I suppose if you want to scream down the highway, drive over sharp rocked river washes, or drag your TT into other such adventures, the robust construction of the LT offsets the fact that they not the recommendations choice for normal trailer use.
Non if this keeps those who think they know better from doing what they want; never was never will.