The signs does makes sense actually cuz you are leaving the main road.
Yes the red truck must give way to the traffic that comes from opposite direction.
So when you approach the intersection to go right you can make that turn without giving way to the red truck, while he is waiting there.
unless the red truck is already moving to left onto the C-D road and you approach to go right at the intersection you must then give way to the red truck.
That is how it works.
1) Truck at intersection waiting you can go to right first.
2) truck driving ont