If I was SLF and was being told to get off the aircraft, I would hope I could ask to speak to the manager and they could show me how and why I was selected to be off loaded and exactly what my rights are/were.
I would have expected such a system to offload would consider such things as occupation. Flights have requested for people with medical qualifications to please make them self known to cabin crew - never heard of a request for say a butcher. Someone with a LAME ticket could also be of a benefit not to offload as with emergency services and even ex cabin crew. In fact any person that could be useful in an emergency.
Hopefully a bit of a review will be underway into this practice and things will then be clear for all concerned.