Indeed. I did find it interesting that the museum made no mention of the atrocities committed by the Japanese military in China as well, or even any discussion of Pearl Harbor beyond a mere mention that Japan attacked it. But then again, that doesn't really have anything to do with the suffering experienced by the populace, as the sins of the government should not be atoned by the governed.
It should be noted that up to 15% of all hibakushas were Koreans, who were seen as second-class citizens in Japan in spite of the government propaganda that annexed Koreans are given same rights as Japaneses. So the lack of statements about wrongdoings of the former Japan empire, including WW2, is certainly relevant here.
(Just in case, Nixon Hidangyo is clearly aware of this and has campaigned for proper recognition of Korean survivors for a long time.)