Alive due to the bomb

DaTech Guy's father was a sailor headed to Japan in 1945 when the atomic bomb blasted Hiroshima.
Without the bomb, would he have survived the planned invasion?
If not, there would not be a DaTech Guy - or his siblings, or their children.
Their existence - and millions more like them - are why we dropped that bomb.
And why it was the right thing to do.
UPDATE: Branch corrected by DaTech Guy