As far as I can tell, the "around the block" spin thrusts are preformed from positions where overhead and side swings would also have hit. I have not been able to produce conditions in which a thrusting weapon could be spun into the side or rear of a blocking player's hitbox by virtue of the weapon's collider not fully extending back to the attacking player, something that only occurs with the pike and only near the end of the thrust animation.
The only way I have gotten to glitch a thrust around someones block with a stab is with a 1 wpf heavy lance [speed = 75] in very heavy armor. Your stab will be so slow in extending you can in fact bend it around the side of someone and drag it into their side with a thrust. It is extremely difficult to do due to the narrow timing window and it can still be blocked if they turn towards where it will come from.
I have practiced trying to exploit the hitboxes a LOT with CanYouBlockDown. I have managed to do some retarded stuff, although none of it is practical.
on topic of the hafted blade.
The thread is referring specifically to the shorter/ not long. The short hafted blade has less reach than most 1handers due to animation, although it can stun lock you on a ultra high agility build with proper footwork. If you know what the "castor swing" is, which is a footwork & side-spam combination, with that you can easily stun lock an opponent to death.
However, if you block twice and don't let yourself get footwork spammed, you'll one hit the agility character trying to pull it off when they think they can spam you.