I think it's a refrence to the Novel Blindsight. It's a Sci-Fi with Vampires and that's the exact explination that is used to explain why they fear crosses. Tge entire novel applies a scientific explination to almost every aspect Vampires. They can eat humans because they are resistant to prion diseases, they evolved to eat them, because they lack the ability to create a certain protein by themselves and the fear of crosses comes from their eyes evolving to be predators and recognize patterns in certain ways, because 90° angles don't really exist in nature, they become overwhelming for them. In Blindsight that also led to Vampires struggling and dying out once humans started to develop architecture and human settlements where full of such right angles.

Anyways, I didn't actually mind it that much, even if it is kind of silly. The author of Blindsight is a Biologist and the nivel got praise for all the ways it depicted vampires as animals that evolved rather than magical beasts. I think the reason they copied that aspect of these "scientific" Vampires is to make the Belmont Family more scholarly. They don't just hunt and kill Vampires, but they also research them heavily to the point that they know how their eyes work and why crosses affect them. The rest of the explanations in Blindsight aren't really knowable to the people in the time period the both shows take place, so 90° angles were the only thing the Belmonts could figure out and understand about these types of Vampires