Yeah and as crappy as it is it being illegal depends entirely on if the employer paid them for the time spent setting up their work station to be 'Available' by 10AM sharp. It only becomes illegal if they're only paying them starting at 10AM when they become available.
Being paid from 10AM to whenever is exactly what the OP implied. They were not paid for setup time as far as I can tell from that text. Are you able to glean more?
