When one is playing 2-3, there are two players at the backcourt and three at the front court. Each has a different role.
Have you ever played basketball? For the 2 defenders in the backcourt, it does not matter which one of them is PG and which one is SG. Are you trying to say that, PG is always left and SG is always right. Comon stop going nuts again.
Your suggestion makes training a lot more random (depending on the luck factor of who is playing more on offence/defence). It would even be better to bring back the old system, than to implement your suggestion. The current version is understandable and works like it is supposed to. Why downgrade?
He isn't against switching the position, but there are 2 guys mostly working at the backcourt since three of them take care of midrange and inside.
I don't think that he want to implement the exact position during a zone, which could have mean that FCP could lead to a guard position training OD ending as a "team training".
he want to combine, the defense training to the role where the player play defensively and not in offense, which makes sense. And off position training getting (much) harder through it too, since the player could play there natural position in the offense.