I would guess that M1 was one oil that may not have needed a formulation change for d1G2,
The amount of testing required for a new formula would never get it out this quickly.
Quickly? They've had 2 years to do it. I think Virtus's comment was centered around a strong suspicion that M1's low-Ca formula, which has been that way for about 4 years now, already took into account LSPI very early on and therefore probably already passed all the dexos1 Gen2 new tests way in advance.
The late "Gen 2" labelling was certainly due to being forbidden to display it before about Sept. 2017.