OK, let's play your "auumptions" game:
The field commanders (not even Truman!) knew we had the bomb, nor did ANYBODY knoew (in Feb '45) know if it would work, could work, or could be built.
So, with enemy airfields on IWO behind the fleet's back as they tried to land on the homeislands, why do you think that Iwo could be ignored.
How long would the air bombardment last?
Of 2400 airplanes that landed on Iwo because they were damaged/shot up, are you going to assume 80% could KEEP FLYING home? That 10% could keep flying another 5 hours to the Mariana Islands?
If 90% of those 2400 aircraft would crash (putting 21000 airmen in the water): Could even 50% have been rescued? What would happen to the bombing campaign/the mining campaign if we LOST 21,000 trained pilots and crew?
According to the Naval Proceedings article that the LA Times article is based on, even the figure above is bogus; most of those landings were for training or refueling or rearming, not because of damage.