The "humanoid" ruling is to stop things like Giants or a race of sentient mushrooms. Demons that can't use magic shouldn't be a problem as long as they are roughly human-sized (Hobbit-height is shortest, Slenderman height is tallest. I'll get exact numbers later), are upright, have less than 8 limbs and NO WINGS. 
I remember an RP once where a race had wings. They won every battle because they could fly above the opponent and rain hell, and no-one could do squit because the armies were very melee focussed. So, no wings.