What you have to fill in there with your logic, TacDavey, is where it leads.
Which is to say, if your implication is true, why DID the Japanese surrender? That's the problem with the tack you are taking, because it is tantamount to saying the bomb made no difference, which is pretty much contradicted by the facts as we have them.
Whereas if you accept that the bomb DID make a difference, then the others are just going to go with "and that was only made clear by the way it was used" and then you are back to where you started, still trying to establish either than that bomb had no effect on the surrender or that something less destructive would have had the same effect on it.
It's hard to deny that one giant bomb causing city-wide destruction has a larger impact on people than lots of smaller ones, even if the death tolls are similar. Especially if you think your enemy has lots of such giant bombs.