I'm reading an article about Chinese privacy concerns should TikTok data be handed over to US companies, wherein we have:
事关国家安全,面对任何可能的威胁都必须零容忍。中国人民关心中国的国家安全利益,关注中国企业正当的海外利益能否得到有效保障,这都是再正常不过的事情,也有足够的理由质问美方的动机。
人民网三评“TikTok交易”之二:浑水摸鱼,想都别想!,人民网,2020年09月24日
I'm struggling to understand the grammar logic in the part highlighted in bold. Google Translate translates this to:
这都是再正常不过的事情
These are all normal things
However, 这都是正常的事情 also has this meaning. So it looks like 再……不过 is some kind of grammar structure used to change the tone here, although I didn't find it at the Chinese Grammar Wiki. It seems related to 再好不过 = "couldn't be better / ideal / wonderful".
Question: How does 再……不过 work?
(I believe I found the answer searching the web, so I thought I'd self-answer. I welcome further answers.)