There are a few reasons I think Ridley is a still possibility.
The first- this is the longest amount of time Sakurai has spent working on the roster of a game. He has stated he doesn't think about it between game development (though I still think that is questionable), and also, that he makes his rosters very early on in the development cycle. Instead, he started conceiving of extra characters for this game, if the ballot is in any way influential at all, as far back as a year ago with Mewtwo.
With that in mind, we also know that Sakurai is in support of Ridley as a character. He has stated he wants to stay true to the character, and has involved Ridley in every game to date. As with other characters, in between development, Sakurai has changed his mind regarding "If a character can work." All has taken was the right inspiration.
If, after this longest cycle of development, Sakurai is inspired, he won't ignore adding Ridley just because he "previously couldn't see him working." If he gets the vision, its going to happen.
Now, will he be inspired? Maybe. Not only has he had much time to consider characters, he has also, potentially been asking the audience for ideas on how to make characters work. If he managed a gander, somehow, at a Ridley that he felt work, he could be as inspired as he needs. Not exactly straw grasping to suggest maybe, the poll did have some validity in some capacities.
All that said, I do expect the attempt at something unexpected. But who knows?