I do agree that retiring PPM so soon would be strange due to its playability with COS, my point was that it does fall in the same “type” of sets that get the short end of the stick in terms of longevity on the shelves, hence in my opinion, that they retiring this year wouldn’t be that much of a surprise.
At the end of the day, this “discussion” is a bit pointless, as not only does this list seems fake, but also because Lego ends up shiffting the retiring set dates quite often, so they might end up extending some of this sets shelf lives.