... because Fixa feels like drawing pointless fluff and ornithologically inaccurate wings, that's why.
And because a) Normal hugs are too mainstream. b) Two blokes (well, male-shaped beings) hugging is not only extremely undemonic*, but also something people tend to notice. Now on the other hand, one being of angelic stock wrapping a wing around an other is immediately dismissed as impossible, and therefore Someone Else's Problem.
*Regardless of what some people have to say about the matter...