Don't be too hard on the union for this, and I used to think the same way. But as my good friend Eric (GG-1), who was at one time the treasurer of his local in Hawaii for several years, explained to me a while back; they have no choice. If the union fails to put up a proper defense, even when one is accused of egregious behavior, under Federal law the union can lose its right to remain a union. So an Amtrak employee caught stealing from a passenger or a teacher caught doing the worst possible thing to a student must still be defended in any termination hearing. And if the employer failed to properly dot the i's and cross the t's, the union is likely to win and the employee will keep their job unless they land in prison via the regular court system.To make matters worse at Amtrak, your union will defend them at hearings, even if they have been accused of illegal actions which they have been caught red handed doing. That means management has a pretty high burden of proof to meet in dealing with such employees.
Put simply; the union must defend the employee, without regard to what morals or even common sense might otherwise dictate.