Sanguinor must be a Living Saint

I mean, isn't it obvious? He is a several thousand years old, mythic, winged (and psychic) figure only appearing in the times of dire need and also said to be a resurrected hero of old (Sanguinius himself or Azkaellon). Only difference is Sanguinor is (or was) a Space Marine while all other Living Saints are from Sororitas or Imperial Guard. But I don't think that really mathers. Anyway, the thing I don't understand is why don't people, both out and in universe, classify him as such. Blood Angels say he is the soul of Sanguinius, Sanguinary Guard say he is still alive Azkaellon and Inquisition says he is a warp creature, meaning nobody is really sure about what he is. I know these theories are close to saying he is a Living Saint but when I see a horned, crimson monster holding a flaming sword, I don't say "this is probably a malevolent creature from Warp but idk", I scream DAEMON and start firing my lasgun. Did you get what I am saying?