Season 1 was a different beast though, because they had to introduce the core group of characters all at the start, so of course we met most of them before we got to hear their specific stories. Now that that core group is established and the storyline is in full swing, there’s not really a point in introducing new characters many episodes before their own story is featured, especially if Aurora and Phillip are only gonna get about as much airtime as Cinderella and Thomas did. In that case, Phillip wouldn’t be significant enough to get a premature introduction in a non-Sleeping Beauty ep.
As for Sleeping Beauty having nothing to do with the main characters, I think it would actually be a perfect parallel storyline for them to tell in FTL, while everyone in SB is in the process of waking up from the curse.