Actually, as a potential ISO+South buyer, I would not find it anything wrong in this approach if the price sit is reasonable.
Guess it’s the key factor: in order to state if it makes sense or not we should know the prices, otherwise any statement is quite inconsistent.
If, say, I have to pay X for the ISO and 1.1X for the South (or North), then yes, I would fell like I’m actually financing the feasibility for English ISO only users.
But if the price ratio is about reasonable then paying, say, X+3,5X (for ISO+South) or paying 4,5X (South with included ISO) is just the same for me.