It seems the letter from Apple that the dev posted on Twitter (which was cropped, excluding the date) was actually from 2019 and not sent recently -- it was his initial rejection before the app was finally approved. A bit misleading, whether intentional or not -- if it was intentional, it cleverly fanned the flames. Props to the dev for gorilla marketing skill.
https://appleinsider.com/articles/21/09/15/apple-refutes-fli...