I am not convinced that the French guy drove the Leeudril route due to the facts supplied by Jeff Gordon.
After 45 km from TR you would have completed the route and be back at Samevloeing. (Total distance from TR via Leewdril and back is 50 km).
Secondly after walking for 15km you will not end up north near Rooiputs, but rather close to Samevloeing (Leeuwdril road is only 11km).
When driving this route you nead a permit and Parks offficers will be aware that you did not return. Even if the office slipped up on the day of departure it would have been noted the next day by SANParks and they would have sent out a search party. The distance is around 25 km from TR to the end of the Trail and that would have taken less than 2 hours reaching him around 9 am. He started walking 10 am only and maybe only reached the Nossob river around 1 pm. It just seems very unlikely that no search party was send out by that time.
Maybe he got confused about the 4x4 track and took the wrong one, but how can you make that fault if the route is clearly communicated to you and surely any one that want to drive off-road do carry some sort of map with you. Leewdril is ~ 16 km from TR and not ~ 43 km as in the case of the Nossob 4x4 route.
I still think as long as you get a permit it is safe to drive the route even in case you get stuck. Remember to take enough water and some food for at least 2 days. Trying to walk back is not such a great idea unless you stuck for 2 days with no help arriving.
Driving the Bitterpan section is also not an issue for a single vehicle. Notify Nossob office of your departure and if you do not reach camp the Bitterpan officer will call for help.
Just follow rules and use common sense and you will not end up in such a situations.