While I share the sentiment that the Metroid game discussion probably doesn't affect Ridley's chances, I'm certainly excited at the idea. Both styles are incredible, and all.
I think the shadow thing is pretty good, though. Far from evidence, but close enough that it holds merit. On a side note that's probably been mentioned already (let's be honest here, everything you could mention in this thread is probably a repeat, sorta like the Original Thought Theory, but on a much smaller scale), I think time does help Ridley in this, frustrating as it may be, because if Stage Hazardley is a reality, they probably wouldn't care anymore. I mean, he'd have been revealed, right? Sakurai wouldn't care, and would probably have just let the Pyrosphere with Ridley be everywhere without a second thought.
So yeah, I'm just rephrasing rather than posting something new, in hindsight of writing that. Snuck in a size joke, at least. Still, the lack of Ridley has to mean something, and damn is it pretty bloody unbearable.
Also, I like Roidley's design. HD Muscle Ridley looks totally badass. Not so big a fan of the game the design originated from, of course, but the design was by a mile my favourite part of said game.