I think the reason why the season is focusing on Beast Boy and Cyborg isn't due to any cross-promotion but simply because it's called Outsiders, which sure, it's a reference to the actual Outsiders team in comics but it's important to remember that this word also means "a person who does not belong to a particular group", which I think applies to both of them.

And yes, Greg Weisman has called Young Justice an "adaptation of the DC Universe first and foremost", it's not really about the actual Young Justice (which is more of a thematic name for the show rather than referring to any actual team).