Why is frisch making this argument

Frisch claims that his views on the atomic bomb were corroborated by his beliefs that had been influenced by his college studies, almost twenty years after the end of Second World War. He further says that writing about the historical significance of the atomic bomb is best explained by the retrospective recognition of the mistakes made by scientists who functioned on the project (Manhattan).

Frisch believes an atomic bomb should have been thrown to Germany, rather than to Japan, and that allies had other options to force the unconditional surrender of Japan. Scientists did not have experience in atomic particle physics to perform demonstration before use, because any demonstrations would force Japan to surrender with minimal human losses, otherwise there was no way to avoid huge human losses by detonating atomic bombs.