Alternatively, it may be that Elidibus is simply lying. We know the Ascians are capable of granting the Echo one way or another since the Sahagin priest had it, and so the whole starshower affair might just be a charade. Like, I genuinely don't think this is a likely explanation--it would be cheap to bring the starshower back as a plot point and then reveal it as a lie--but it's always worth keeping in mind that Ascians use deception as a tool liberally.