If that's the real issue why don't they simply say so? In my experience most food on Amtrak isn't anywhere near hot enough to burn skin. When assembled to go it's packaged and repackaged to the point that it's virtually impossible to spill it on yourself. The hottest liquid in the diner is probably the hot tea and they let almost anyone walk away with that. I'd have to be Mr. Bean levels of klutzy and curious to harm myself with AmChow.
I have to agree with DA here; I just came back from the diner following our SCA who was taking a room service lunch back to the accessible bedroom. Everything was packed in plastic and carried in a large paper bag with handles. The days of Pullman porters juggling a tray of china and silver between cars are long gone.