This. I strongly believe you guys are looking too deep into the whole shadows argument. It doesn't prove anything right now, and it shouldn't be treated like a tangible argument at this point in time.
While the shadows have posed an interesting topic of conversation, it does not directly mean anything. The only thing I have to say in regards to shadows is that they do not reflect the actual size of someone or something. Depending on the angle of the light, the shadow can change size.
For example, if I stand outside and the sun shines at a particular height, it can either make my shadow longer or shorter, if we're talking in terms of shadows. So with this in mind, and the fact that the shadows are probably generated by some sort of physics engine, it shouldn't be taken as anything concrete.
EDIT: You guys probably won't like me saying this, but the only concrete information on Ridley we have right now, is that he was shown in a clip that had a subtitle hinting at other bosses. This clip was after Yellow Devil was shown on Wily's Castle.
You can take that for what you want, but that is literally the only legitimate information we will have until E3. Unless something concerning Ridley gets revealed via POTD.