We see these incidents from our own point of view as flight crew.
The essential difference between 'our' point of view and the police's is the pivot point in this debate.
WE wish to see the situation resolved quickly and safely. Thus a prompt diversion followed by a prompt disembarkation is the only correct course of action. After all if it is 'worth' diverting for then the a/c must be emptied even though loss of life in a ground explosion will probably not be as destructive as the same explosion airborne.
The police, on the other hand, have completely different priorities.
Their main objective is not to do anything which could expose themselves to criticism or liability after the event. In other words if a cop is killed or injured during the incident, and the police are seen to have acted carelessly and this led to the injury or death, court action will surely follow. This must be avoided at ALL costs.
This same approach led to the police leaving a woman who had been shot and wounded, to die, rather than enter a house, despite being repeatedly assured that the gunmen had left the scene. (it was a multiple shooting at a BBQ in England a few years ago).