I don't know, I'm no instructor, maybe it is easier to center your stance on a directional twin, I just don't understand how that is going to make riding switch easier when a directional setback twin is already designed to ride switch, its just performance orientated for riding regular.
Extreme placement to center the stance is simply going to move your axis away from the waist of the board and put you on or in front of the flex point of the tail.
To me that sounds like it is going to make the ride worse both in switch & regular.
Now I understand your concern about performance, but skidded turns? That technique is not far away once the rider has learned to get on edge. And while it's true you'll get equal performance from the board if it's a true twin, the rider is still going to have to learn to ride the board switch efficiently before they can expect any performance from it.
Maybe one of the instructors can share the knowledge.
The way I understand how "most" directional board are supposed to work is as follows. The tip is longer and more flexy so that when you're going fast, it will absorb the bumps furthur ahead of your feet so it won't vibrate your feet as fast and make you lose stability. The tail is stiffer and shorter so that you will get more "pop" comming out of turn (carved mostly) as well as making it easier to "rudder" to a skid/stop.
So since you're a baby again when learning switch, I would say your primary goal is to build the balance and muscle memory to heel-toe-stop, etc. and shouldn't be going fast enough or carving to take advantage of the above mentioned design features. Of course, you can always mount your board backwards to begin with, but they you might make non-switch riding worse I guess. I mean, ppl do offset mounts all the time (e.g. powder days) and it doesn't "mess you up" all that much because it's not exactly at the waist.