This is absolutely true, but I have trouble seeing the relevancy of stating that in how it relates to the fact that two non-military, civilian-dense cities were bombed. Normally killing hundreds of thousands of civilians for political gains is considered terrorism, easily a warcrime, despite the fact their government may be driving its population to horrible atrocities all over Asia, or not doing enough to prevent them. In fact I don't think the US really covers this enough, it's usually brought as merely the end of a bloody war, when you can find many generals who opposed, arguable claims that the bombs were the first political move in the cold war as a gesture of power towards the Soviet Union and as a way to have Japan surrender to the US rather than the allies, and therefore under US terms which would cement US-Japanese relations (which are solid to this day), as a test, and within a context where Japan may have offered to surrender under similar conditions as the US ultimately demanded, many months earlier. To be fair, there is no academic consensus on any of these points, but many are credible and sensible claims for which evidence does exist, and my experience of the standard reading in US culture makes little mention of this. It's mostly seen as a necessary evil that saved many lives by ending the war abruptly, which isn't incorrect, but far from the comprehensive truth or the only credible historical narrative.
But as for Japan's whitewashing, yes, in and of itself, viewed separately from the nuclear debate, you're absolutely right. It's quite astonishing they haven't gotten this right yet, and with what power a wrongful national narrative can continue to exist in the age of internet, globalisation and relatively little Japanese censorship. You'd think the latest generation would be acutely aware of its history. And it's not as if they haven't changed. They've done more than enough to consider themselves among the most civilised countries since then, of course there is a sense of shame but we're approaching an age where nobody during that time was alive, and where even the generation after it is on their way out. Internally Japan is long overdue in recognising these parts of its history in full, and I think purely internally few Japanese really would have an issue with that, as painful as it would be, just like I'm completely comfortable as a Dutch person to acknowledge my country's colonial and slave history. But these things are particularly externally, politically sensitive, in terms of Japan's international relations with the various powerhouses in Asia (China and Korea, and populous emerging economies like say Indonesia). Similar to say, if I were a Dutch politician I may be more concerned how our standing in the world changes when recognising the full extent of our colonial history (e.g. apologising for certain political executions the Netherlands committed are still controversial) Just like say Turkey and the Armenian genocide. Although even here as an outsider I think it would warm Japan's relations immensely if it were to reach out in sympathy and make at the very least symbolic gestures like small reparations.