I don't know what the situation was in this incident, however, I drive a tractor trailer.
Not everyone knows about "The Dragon". US129 is a Federal Highway listed on a map just like any other. It spans nearly 350 miles between Knoxville, TN and Macon, GA. "The Dragon" is only about 3% of it. There are no warning labels on said maps, and unless you get a local level map, will not show just how curvy that 11 mile stretch is. And once you're on it, you're done. There are no turnarounds. I'm sure there's alot of truckers who get caught on it unaware. There are also the locals who travel it on a regular basis, and will usually have a "escort" of sorts riding ahead to warn other motorists. And I'm sure there are those who "chance it" due to fuel/toll costs. Approx. $100 saved is alot of money. Especially if you travel it on a regular basis. (twice a week adds up to nearly my weekly paycheck)
Tractor/trailers are nothing new, or all that uncommon, on The Dragon. It's only when something bad happens that you hear about it. In fact, tractor/trailers are the only vehicle not ticketed for crossing the double yellow on The Dragon. Because it's unavoidable. And they can't "ban" large trucks from a Federally Funded Highway (no more than they can "ban" motorcycles from it... and they have considered it due to the high fatality rate of motorcyclists on it), but they do "recommend" alternate routes.
Statistically, people die on those roads far more by there own doing, than with other drivers involvement. And statistically it's a non-local who's unaware of the dangers of the roads.
Having said that, I have never been remotely close to even the southern tip of US129. My routes are, and always have been, in LA/MS/AL/FL, and below I-20. I can't say I would never be on The Dragon in my work truck, but I can say I would use other roads if at all possible. I have been on it a few times on my Hayabusa, and am familiar with it.
I would also like to add my condolences to the rider and his family/friends. It's a sad situation any way you look at it. But I also have to question... I'm sure the truck wasn't speeding. In fact, I would imagine he was going below the 30mph posted limit. How fast was the rider going that he couldn't stop/swerve in time to avoid a collision?
Sometimes people need to take responsibilty for their own actions as well.