"doesn't work for all projectiles" - well, duh. Taylor never claimed it would.
Ridiculous misuse of a simple, useful comparative calculation.
Muzzle energy is far less useful because the squaring of the velocity,
while correct in the sense of the physics, does NOT correlate with
effect on target well at all. TKO is a momentum calculation with the
addition of a consideration of caliber. Nothing more, nothing less.
Carrying any of these numerical calculations to ridiculous cases is pointless.