Looks like an elf on steroids. Lose the ankle and wrist weights and it works, as long as there's no flashing of pointed teeth, horns appearing, or any of that sort. As long as it looks like an elf, he can be in without disguise. Note that going around telling people he's a demon openly isn't allowed; do that in PMs. If he's going to look different to an elf in any unusual way, he's to be in disguise, exactly as the rules state.
Really, this picture is easily covered by the rules as stated under the setting; my comments just serve to reinforce that.
Siani