Then you have access to the traditional dining car, which is not the same as, say, the cafe car on ordinary Amtrack service.
In order to provide service to all sleeper customers in the dining car, you must reserve a time slot during meal times. Between meal times, the car may be closed for changeover.
So, simply taking the facts as stated in the story, they were playing cards at a limited dining table during breakfast hours, when there is high demand for tables from all of the other customers in sleeper service.
I could probably make some bets on some of the things left out of their side of the story, but I sincerely doubt they were thrown off for playing cards.
A sincere question for you, since you have taken Amtrak a number of times (and I am assuming on a service class other than, say, the Northeast Corridor). Based on your experience, what has been the general demographic composition of, say, persons in first, business, or sleeper service in comparison to Amtrak employees?
There's an obvious subtext to me here.