perhaps one should not forget, that someone might agree to a PX request by crew ctl during the roster period. How are you supposed to know if the bunk applicant has signed the form or just simply agreed to a roster change?
Are you going to give them a lie detector test (meet the parents style)?
It's not that hard to look up a crew members published roster to see who is scheduled to px vs. a crew member simply agreeing to it. Also, I would assume most would not straight-up lie if asked if they were rostered or requested to px.