When I think of Hiroshima and Nagasaki I think of a million less dead American GIs, and at least an equal number fewer dead Japanese. War is war. The Japanese military elite are at least equally responsible for both cities, and especially for not surrendering after Hiroshima. It’s easy for you folks to sit on your high-horses with 75 years of distance, and little knowledge of the circumstances, and espouse how evil the Americans are for using the atomic bomb.
Secondly, the exchange student is wrong in saying that Fukuoka was an alternate target. Kokura, SE of Fukuoka, was the primary target for the second bomb, and the secondary for the first.
As for Richland using a mushroom cloud for their mascot, it’s no different than using any other symbol of war in such fashion.