I am even more puzzled that approach radar were not concerned by their height, heading and airspeed. It must have looked rather strange at 15 miles out and getting more critical by the minute. Was this ever questioned by radar ? They must have thought they were descending a tad early !
Approach control had already handed the flight over to tower well before they got to KAAO, and the tower had already cleared them to land. So it's very likely that no one was watching them on radar, or that the tower might not get height, heading and airspeed indication or alerts if they even have radar.
Perhaps a future local procedural improvement that can be made is for approach to not hand the aircraft over to tower until after passing Jabara.