Different strokes for different folks.
But why is it so unacceptable to allow a healing spell to be created for the game by the designer (which, given SJ's reputation for carefully thinking his way through things, will be well-balanced in the context of the rest of the game) and then, if you feel so strongly about denying it to your players, simply saying that the spell doesn't exist in your world? You can have it your way, and other people can have it theirs. Rather than "policing" how other people play, why can't we just say; "Okay, no big deal, it doesn't work that way in my world because mana can't interact with living tissue in a non-confrontational way -- it can blow you up, but it can't put the pieces back together again."
As the GM, you can make your world any way you want, but why try to enforce YOUR rules on anyone else?