I don't think this is a question of what happened anymore. That seems quite clear. The real question is WHY the switch was not aligned for the main. 99% sure this one isn't Amtrak's fault, they were the victims here. Someone at CSX is responsible for this, and when they figure out WHY, they'll also know WHO. It's a short list.
Of the three recent accidents, only the Washington State will be on Amtrak. This one and the garbage truck, they couldn't control. Outside factors.