teitan
Legend
I suspect the line is that the "fantasy versions" of the pantheons count as discussing "mythology," whereas most discussions of Abrahamic religions count as "religion" because of their ubiquity in modern culture. The religion is sufficiently intertwined with the "gods" that you can't fully separate the two. But discussing the way they handle angels on Supernatural doesn't cross the line.
And yes, there are Pagans and neo-Pagans, but most people know Thor more as a comic book or legendary figure than as a god they actually worship. So discussing those gods in the context of the mythology that's been written about them is fine.
kind of a weak argument considering, for example, Iceland is now a largely Pagan nation dedicated to the Aesir.