I disagree with you on both points. They seemed to go out of their way to acknowledge Ulysses in Reborn, the solar flare in a surprising number of places (the latest and most surprising being Super Sons), and he's a Johns creation that was likely set up all along to be an antagonistic frenemy to Superman. They'll likely say something to the effect of his Earth parents being the only thing he has left to fight for. He'll likely be a no-nonsense-justice counterpoint on the team (likely to Steel given he's so directly inspired by Superman) allowing for sufficient friction on a team of people who are kind of like Superman in power.