The way I see it is: either way, Sakurai made the best choice in the direct.
Showing Ridley's shadow confirms he is in the game in some way shape or form. It's alluded to that he is a boss, but left ambiguous. Some people will expect Ridley to be only a stage hazard/boss. Those people's expectations will be met if that becomes the case. Other people expect Ridley to be playable. If he is a hazard/boss, those people will look back (hindsight is 20/20) and most likely admit that it was obvious and they shouldn't be let down. If on the other hand Ridley is playable, those who said he won't be will realize it was a massive troll move and those who say he will, will be happy.
No matter what happens, we're talking about it and that is good for publicity. No matter what Sakurai wins.