I agree Sakurai didn't do an amazing job trying to mislead us with the Boxing Ring/Little Mac.
Just like I don't think Sakurai is doing a great job trying to mislead us about Ridley. Just like Little Mac he made it obvious Ridley was gonna be playable.
It's actually about the same.
Little Mac stage
At first glance: "Well it's a boxing ring but it says smash bros. on it so it's definitely not a punch-out stage. This might even deconfirm Little Mac."
After actually looking: "Wait, it may have the smash logo but otherwise this is LITERALLY a punch-out stage."
Ridley
At first glance: "Well they mentioned boss characters at the same time they showed RIdley's shadow. Ridley deconfirmed."
After actually looking: "Wait. He's really small for a boss and really SLOW for a boss on a pretty big stage, the stage most likely has some other lava-related hazard, and it's pretty obvious with the lack of sound, mention, AND the bizarre behavior and camera angle and zoom choices that this was staged."
Will it reach the same result? E3 shall be the final battle of the Ridley Wars before the beast is sealed away for another six years.