What makes it strange is that no NPC can tell that the dude is a Nosferatu. I mean a guy from the Dawnguard comes up to you, and says that the mysterious stranger with the bright glowing orange eyes, pasty white skin, and pointy teeth is a Vampire. And they don't believe them?
At least let me cast the sunlight spell on him as a test. If he doesn't burn to death he's not a Vampire, if he does then nothing of value was lost.