Doing this to police firearms would sure do something to prevent officers from being shot by their own weapons when taking suspects into custody.
as someone that has had a member of family while serving as a police officer shot in the line of duty with his service weapon (survived) that minimal advantage is far outweighed by the abject failure of all the scanner systems thus far tried in the real world.
Battery failure alone makes it a useless, of not why do all our EO sighted rifles have back up sights ?