I understand your argument, but it is based on error.
You could not pick #2 rationally, because you would have already, as Truman did, had the combat experience of Saipan and Okinawa to base your estimates of military and civilian casualties.
To condemn another 250,000 of your own soldiers to death needlessly to argue a moral principle would have made you complicit in the murder of 250,000 innocent men.
The whole question of millions of Japanese dying also would just be icing on the cake.
In 1945, for a President to do any less would have been a grave moral error.
Sincere request: I'd like to understand you better.