Bearing in mind that the author warned you that not everyone would (or should) agree with everything he wrote, I thought it a useful stimulus piece.
Now, I suspect no one here will agree with me on this, but for my money the part that was overstated involved terminal ballistics, a subject that I believe receives excessive scrutiny in the personal defense realm. How a aggressor target responds to being shot by a defensive shooter depends on such a wide variety of factors that I suspect that if you could simulate the complete array of possibilities and probability, by caliber, you'd find such overlap that distinguishing between the major rounds would be difficult.
For me, I have no doubt that if you gave me (or I took for myself, pounding heart notwithstanding) the time to place my first shot as I should, I could drop anyone not wearing body armor with one shot from a 2-inch .38 loaded with a wadcutter and 2.7 grains of Bullseye.
I have always believed that the signifcance of caliber has less to do with what happens with a well placed shot as it does with what happens with a poorly placed shot. That is to say, the major advantage of a hand cannon is that you don't have to be a marksman (most of the time). This is not an invalid consideration, especially given the difference between range conditions and assault conditions, but it is a consideration easily overstated.
Now I duck.
Edit for afterthought:
There is another consideration that I think our author of the moment entirely overlooked. As do most folks who purport to tutor in the field of self-defense.
We are all trained to believe that deadly force may be used in self-defense only in a case of abject necessity. This, we are led to believe, means that the aggressor must be allowed to advance his aggression to a point where his intentions are so irrefutable that no jury will hold us culpable for interceding.
However, real experts in combat will tell you that this is the wrong way to fight. Once you have decided that the dude (or group of dudes) approaching you is intent on a result that you won't like, the best defense is to take the offense. This means drawing the line far earlier in the progression than the worry-warts counsel, and once that line is crossed, opening fire. The upside is that you have to time for good first shot placement, since, pardon the expression, at this point you are calling the shots. The downside is that you may be criticized afterward, possibly with some consequences. The upside is that you'll be around to hear the criticism.
There ain't no simple answer.
