Akainu did not simply smother Ace's fire putting it out (basically it's a phenomenon by which magma is preventing oxygen to reach fire in order to have it burning) , he literally burned it. This is what canon tells us. It tells us that magma literally burns fire. It does not put it out.
You can't simply nullify another element differently in OP. Ace would have still been capable to protect himself with fire without letting himself be burnt differently, overwhelmed or not, that's a different matter.
So this is just an attempt to make things fit. But OP is plenty of disastrous physics. I particularly know it since I particularly care about that field.