Song is kind of a bad candidate for that, considering he's pretty old and well-known enough people will notice him developing powers.
I mean, that's also why we've been brainstorming ways we could get around that ever since he was revealed as a candidate? Like giving him transformation or Deadman's powers, or figuring out ways of de-aging him.
My overall point was he's likely better candidate for cover than Yara, with her getting powers reaching A-S right after Hero Worship makes it more sus, even with her being just at the right age of convenience.
Of course, you could argue about Soraia or Shelley as the next candidate as well, but 1) we sorta already have a plan for Shelley that was discussed before, which requires her to not go now, 2) compared to all others, Soraia has like the least discussions on what combination is right for her, which made me unsure of where to place her, 3) I still want a front liner, which is why I'm forwarding Song, who Bitterman had revealed a synergy that could be good for him, and 4) if we're talking about REP problems, while Song indeed has the biggest problem in that regard, don't forget Soraia and Shelley are public figures of the community in Apiary, the former even moreso as an administrative staff. They all need cover stories as well (tho depending on what may happen in coming turn, with Crusade and Philosophers pressuring JU more and more, they may not be as necessary for long)
There's also Cain of course, but I've posted my stance on him before: I want him to have more screen time and character moments before we officially decide to really induct him to the crew.