Dan,
I'm glad that you got something for the trouble that you feel was fair to both you and Amtrak.
If I bump into one of the attendants that I know well, and I know a few, I'll try to find out what the policy is. Don't expect an immediate answer though, as I currently have no Acela rides planned for the next month or so, and of course I also need to pick the right run to meet up with someone that I know will tell me the truth.