Uhhhh, wwwhhhhhhhat theory indeed! Whoever said that must be someone smart!
Lol, well to put it plain and simple; if Rarity puts him in the Friendship Zone, and Ember the defiantly not Skyrim dragon also sees him as a friendly(zone) dragon, who do we know he's in a much better relationship who could be "anything he wants them to be" with him? Who I tell you, who!
... It's Thorax, that's where I'm getting at xP Dragon and good Changeling being together in harmony and morphing into anyone he wishes as long as Thorax get's love even if it's for another just to make Spike his first friend happy