It derived from this post: https://kiwifarms.st/threads/4chan.37222/page-656#post-21113619

Before a kiwifarms moderator edited their post (see the spoilered part), they'd accused kaguya of being some completely other person that also happened to be using Kaguya from Touhou as an avatar

They probably just looked up "kaguya" and assumed everything they found was the same person. So much for that "PHD"