Considering that later ports often lean to LESS sales overall, I doubt that is the case.
I think he's talking about double dippers. The fact that this is a late port will indirectly lead to some more sales for the other versions, and those same people will end up getting a second copy on switch. This tactic worked with games like GTA V on PC (and MHW), although this is on a lesser scale, of course.
So he's talking about the combined sales of the game, not just the switch version.
Another reason I think is to not overshadow that other dragon ball game on switch (whats it called again?), and give it some time to breathe.
Bet with Intrinsic:
The Switch will outsell 3DS (based on VGchartz numbers), according to me, while Intrinsic thinks the opposite will hold true. One month avatar control for the loser's avatar.