The air dates are correct. SInce this series is an AMC original, not an AMC+ original, the air dates should be the dates the episodes air on the linear AMC channel. The AMC+ dates are considered digital previews.

That's asinine reasoning. We live in a digital age, if the content has been released through a digital platform, it has been released. Period. As much as I'd prefer to use TMDB instead of IMDB, stupid decisions like this are just one of the reasons IMDB will always (unfortunately) be the better platform