I certainly can't argue with your logic about it's use as a possible
weapon. An officer's primary concern is personal safety - his own, and
those around him. The ability to strike with the flashlight can't be
ruled out.

But at night, or in a darkened room, where, of course, a flashlight is
most likely to be used, there is a more overriding reason. The bad guy may
be armed, and then the light isn't likely to be used as a weapon, but can
contribute as a defensive device.

Most people who are untrained in the use of firearms (bad guys) tend to
jerk the trigger of a gun when they shoot it. In fact, actors who are
untrained in the use of firearms are often seen almost shaking the weapon
at their target, they squeeze it so hard. That jerking action tends to
make the gun shoot low, and to the right for a right handed person.
However, at night, an untrained person shooting a gun tends to shoot high
instead of low, and still to the side that they are shooting from (usually
to the right). This is probably because they unconsciously raise the
barrel too much in an attempt to see the front sight better.

What do they shoot at? The LIGHT, if a police officer is holding it. So a
right handed officer, holding the flashlight in his left hand, has the
best chance of survival statistically, by holding the flashlight as far up
and to the left as he can, thus the overhand grip. If the bad guy shoots
at the light, the shot is likely to go even higher, and even farther to
the right (the officer's left), therefore missing the officer.