OK, first off, the IHR is a terrible source. They are a Holocaust denial organization. JUST FYI AND ALL. You should tell your friend to be a bit more wary of their sources.

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The Japanese were not on the verge of surrendering before the bombs were used. There was a faction of their high command that was exploring a diplomatic end of the war (a conditional surrender) that might be mediated by the Soviet Union. They were not the majority of the high command and it was still exploratory.

Does that matter? Yes — the US was aware of these attempts by Japan, because it had cracked their intelligence codes, and knew, for example, that the biggest stumbling block was the question of what would happen to the Emperor in the postwar. The US high command factored this into some of their own decisions about the conduct of the end of the war (and also deliberately did not make it easier for the Japanese to surrender, by modifying the unconditional surrender demand), so that's a necessary detail in understanding the end of the war. It also contradicts the "orthodox" narrative that the Japanese position was entirely a fanatical "fight to the death" sort of thing — the Japanese high command was divided and potentially interested in exploring surrender without invasion prior to the bombs. But that is not the same thing as being on the verge of surrendering, at all.

There is a separate question of whether the atomic bombs did end the war, or whether the bombs were necessary since, after all, the Soviet Union's invasion of Japan (which happened soon after the first atomic bombing attack) also greatly affected the position of the high command on the war's outcome, and whether that means the weapons weren't necessary. These are separate questions, though.

Most historians don't buy the entirety of the Alperovitz argument, but they also don't buy the entirety of its opposite, either (e.g., the "we had to use the bombs to avoid an invasion" argument). The reality is somewhere in the middle, as far as we can tell, an answer which of course satisfies nobody who wants to use the atomic bombings to justify their present-day political positions. There were several alternatives to the bombings that did not involve an invasion, but it also wasn't like any one of them was obviously better (or that anyone at the time was interested in searching for alternatives). It wasn't a huge conspiracy (like Alperovitz might have you believe), but it also wasn't some perfectly executed strategy either (the bombing of Nagasaki, for example, was almost entirely without strategic oversight). So it's complicated. My favorite source for unpacking a lot of that complicated is Hasegawa's Racing the Enemy, which explores the end of the war from the US, Japanese, and Soviet points of view.

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But for the love of god, don't spread IHR links. They are garbage history, both because their own arguments are tainted, but also because their association with any non-garbage argument unjustly taints it. Alperovitz is generally thought to be not totally correct, but he's not deserving of being associated with the IHR.