> In fact, if we’d told the Japanese we would let them keep their emperor, they almost certainly would have surrendered. The Soviets had just entered the war in the Pacific
Er, no.
The nuclear bombs were dropped on August 6 and August 9. The USSR announced it's declaration of war at 11pm Trans-Baikal time August 8, and began invasion at 12:01am August 9. So, at the commencement of the atomic bombing, the Soviets had not just entered the war.
> and we wanted to end it before they captured much territory.
So, what you are saying is that he Soviet entry into the war, absent the nuclear bombings, would put pressure on the US to grant Japan more lenient peace terms. Maybe that's true, but I'm not sure how that's an argument against the bombings.