The formula for kinetic energy is K.E.=1/2*m*v^2. That’s what it is, regardless of what Mr. Taylor might have thought.
It sounds as though Mr. Taylor was using the formula for momentum (p=m*v), rather than kinetic energy. While momentum may indeed be a better indicator of a bullet’s “killing power”, it is not the same as kinetic energy.
Of course it is not the same. That is the whole point.