Where was it confirmed that a character can't be Boss AND Playable? Pretty sure it never was said so. You don't know what Sakurai is thinking, so please don't act as if you do. :/
And no, having a playable Ridley next to a bigger Boss Ridley isn't strange. This is Smash Bros. Where Olimar and Pikachu are giants, where Space women battles plumbers, where Rest kills, where Mario can fight Doctor Mario, etc etc. Will Ridley next to Boss Ridley look off? Of course. But so does pretty much Everything in these games. It's strange when people brings up logic in Smash.
But back on topic. I now know why Sakurai said 'there will be no flippers'. Cuz' the Balloon Stage has them. XD
... which means Sakurai kinda lied to us. Again. Now that's a good troll.