It is a remotely-controlled device, jury rigged for a purpose that is not at all its use.
I know people will become uncontrollably outraged about this, but it's a standoff weapon. Just like a spear, a bow and arrow, an explosive tossed through a door or window, a gun, or even a vehicle employed as a weapon.
The legal standard for lethal force is the same. Beware of academics or other commentators who will claim this is some kind of new territory for which there is no legal standard and that we have no idea how to approach.
But by all means: pretend this is an "Unprecedented Shift in Policing" instead of an improvisation under nightmarish circumstances.