Either the bomb or the Soviet attack, by itself, arguably would not have been enough.
First he argues that the nuclear bombs weren't that important, or different from our other bombs. Okay, fine. Then he argues that we persist the myth that the bombings ended the war because it helps us feel better about having dropped them. But if they weren't that different from our other bombings, why would we even need the lie to feel better about them?
Similarly with his timing. August 6th -> 9th was (he feels) both too long a wait to deal with the crisis, but also too quick, since the preliminary report about the bombings didn't arrive until the 10th.
And invasions: they didn't surrender at the threat of a possible US invasion, but a possible soviet invasion caused an immediate surrender?
As an argument that the Japanese surrender was more complicated than "we dropped a bomb, they surrendered"—well, obviously that's true. History is never that simple outside of textbooks for children. But in his arguments that it was irrelevant, he spends too much time contradicting himself.
For example, it claims that they couldn't have surrendered because of the destructive power of the bomb, because there had been worse bombing raids. First of all, the Japanese could have considered those bombing raids to have been lucky. It is also possible that the raids that caused more damage were in much larger cities, such as Tokyo. It is also possible that the psychological effect was greater for nuclear weapons. The Japanese had no idea how many nuclear weapons we had. They may have thought that the first two were warnings, and if they didn't surrender we would start dropping 30 every hour until they were obliterated. If, as the article says, bombing raids were carried out by 500 bombers at a time, why didn't the Japanese have every reason to believe the next major raid would drop 500 nuclear weapons?
The article also contradicts itself. It says that the bomb couldn't have swayed the supreme council, since news only arrived after they had met and the vote to surrender was deadlocked... I mean, what? Only if they had already surrendered before they got the news would the bomb be proved irrelevant. They voted and did not surrender, and yet after news of the bomb arrived they in fact met again and then did vote to surrender.
There is no doubt that the bomb would have a huge psychological impact beyond merely the measurements of the damage it did.
Thought experiment: A boxer is set to fight the Champ. Which of these situations is more likely to cause the boxer to back out of the match?
1. The boxer learns that the Champ once beat another boxer for round after round, and in the 12th round the boxer finally died from his cumulative injuries.
2. The boxer learns that the Champ always carries a gun to the ring and shoots his opponent in the face before the fight even starts.
In one scenario you may think you are going to lose, but at least you'll go down swinging and maybe you'll get lucky somehow. In the other, he is going to murder you with a bullet and all you have is boxing gloves and no shirt.
108 U.S. Aircraft Carriers bearing down on the Main Islands had a little bit to do with surrender.
Certainly if we didn't have a large conventional military, which is pretty much the exact same as saying the Japanese were winning the war, then they wouldn't have been surrendering, since countries don't surrender just before winning (usually).
The question is whether they surrendered specifically out of fear of nuclear weapons, or weather it was because the Soviets invaded Manchuria. I'm sure neither was great news, but it is not clear why they would be especially worried about the Soviets declaring war, I mean they were at war with us and not surrendering for years, and we had 108 Aircraft Carriers!
British Pacific Fleet had 8 additional carriers: https://en.wikipedia.org/wiki/British_Pacific_Fleet