Taylor's calculations are not for penetration but knock-out value where the increased frontal area of the larger calibers can make a difference. You still need to maintain adequate velocity of course. You also need to come close to the brain.

For pure penetration the .416 magnum rounds and the .500 NE both have a great reputation. Still the .45s have a better stopping reputation than the 416s...

I would be happy with a .500 NE as I have read good reports of its effectiveness, but I would not assume that it would always be better than a 750-grain .577 at the right velocity.

As I said above, I would not over-generalize from this incident, and I would certainly not indict Taylor based on it.

My experience is pretty limited so I tend to listen to those with more.