Just let him have his fun. Heck! I've been here for years and I've never gotten a single complaint about my OC. Let him have his Time Lord Alicorn. I would like to know how you made that image though.
So? If this was an RP, I'd say differently but for fun on a forum, who cares? Also: Fun. All the time. It's totally allowed. Because it's fun. Can't stop us. Even with full grump active.