>I think his explanation was that right angles don't appear in nature

Which is weird, because they do.

I remember reading this, and looking out my office window where the branches of neighboring tree (denuded of leaves because it was winter) made three or four near-perfect right angles in projection (along with intersections at other angles).

My initial reaction to this was, only in approximation. But the cross would also only approximately be a right angle. So good point.

Lots of minerals break at right angles.

I watched the video and that's what the fictional presenter says. I don't think it really makes sense though, but maybe you can get passed that because the species coming into existence at all is so contrived and unlikely?

The vampires appeared to have less of a gene pool and more of a gene cleanroom. Knife edge stuff there.