Rule #1: You shouldn’t drive a passenger train 75 mph if you are asleep or on drugs.
I believe the SC amtrack was on another track stopped to allow passage of the CSX freight train that has the track priority.
It was noted on another thread that the Amtrack engine although stopped, encroached on the main taack and was struck by the oncoming freight train. From what I saw, I can believe that to be near the truth.