While this is a fun meme, it badly mischaracterises Lewis' attitude toward speculative worldbuilding. Prior to The Chronicles of Narnia, Lewis was best known as an author of theological science fiction, and he carries that approach forward to Narnia. Indeed, that's why he was famously so hostile to allegorical readings: Narnia is situated within a multiversal Creation in which God the Son incarnates to deliver salvation to each world in a form suited to that particular world's idiom – it's unnecessary to interpret Aslan as a symbol for anything, because textually he literally is the second Person of the Holy Trinity incarnated in a form suited to a world of funny talking animals. Heck, there's even a complicated theological explanation for the lamp-post.
Granted, I'm sure Lewis was having fun with Santa Claus popping up in Narnia to give people magic swords for Christmas, but that doesn't mean he wasn't also massively overthinking it. He and Tolkien were much more alike than I suspect either man would readily admit!