C’mon Sam, when Moshe Rabbeinu built the Mizbei’ach and called it Hashem Nisi, He was following Avoda Zara? As you really telling me that the Rambam’s reasoning is that the Torah went against the norm here, while his whole purpose in the Sefer is to give rational?
Secondly, you agreed in the past not to call this Avoda Zara because even the originators of the non Jewish custom in question weren’t worshipping anything by doing it.
But really, it makes no difference how it seeped in. It’s not even an exact copy. The claim is merely that it can be traced to that other custom/ritual. When I draw a key shape on my Challah I am not following any Chukas Hagoy, whatever a history book might say. Eating Turkey on thanksgiving, perhaps, but this?