The thing about that is, even though you might believe it would be the logical thing to do, it doesn't mean it will be done. You might say it makes perfect sense to add Ridley in Project M, but the PMDT might not even care about adding him. They might not even add the leaked characters, because at the end of the day the devs will do what they want with their mod.
Ridley's chances of being added officially are slim. His chances of being added UNOFFICIALLY, however, are infinite, because people like myself wouldn't hesitate to add this PSA to P:M using a P:M + BrawlEx pack, because it is a gorgeous PSA and a lot of time and effort was put into it.
Of course, if you strongly feel the PMDT will add this character, that's on you. In no way can I alter your thoughts. But the way I see it, those guys might not add this PSA, and whoever wants to use it would have to either replace Pit or add him with BrawlEx, which is truly not that hard to do.