I can think of many terrorist events that have been carried out by numerous persons with both a single device and multiple devices.
Flags that would be raised from outside aircraft that is still flying could be.
His name
Nationality
Age
Sex
Religion
Can match a radicalized person with terrorist intentions - was he a lone wolf or an accomplice. Would the accomplice be the real hiding cell waiting to blow up some special forces persons (killing cops is a favourite) and this person just a decoy?
Once his mental record came to light and investigated the likely hood of knowing if it was actually a bomb or if he would be involved would give a better understanding of the gravity of the situation.
So to immediately have a squad of police meet the aircraft on its arrival and either remove the bomb and Bluetooth speaker or offload pax could be the trap and key for the sleeper to detonate.
They would decide when to have maximum effect by the announcement of Captain or Cabin Crew to either stay seated or exit the aircraft.
Interviewing pax is different from clearing them as possible suspects.
* They use to give young kids a bit of a clip under the ear to straighten them up - they get damned for doing that now!