I wonder if the security people were operating under a general expectation of concluding such an action within a certain amount of time, or if they were ordered

I wonder if the security people were operating under a general expectation of concluding such an action within a certain amount of time, or if they were ordered in this instance to conclude within a certain amount of time. I also wonder if the plane actually was "overbooked," or if the need to get four crew-passengers on the plane was due to a sudden and unforeseen event. Claiming "overbooked" may give the airline some advantage that not overbooked would not. No idea what the rules for overbooked vs not overbooked are in this case, it just seems weird that exactly four people needed to leave for these four crew members, and not, say, five because of a real overbooking.