Why so late?

He's not a character we're all supposed to unlock or 7* on his first appearance. Kudos to you if you can, but this is basically CG telling us to get First Order and Resistance squads going.

Think back to the Thrawn event, and Phoenix panic farming. Thrawn is immediately useful, it's true, but since that event Phoenix has been proven to be a good investment in a number of ways. Galactic War has gotten more challenging, but Phoenix can usually overcome it with good gear. Territory Battles has a Phoenix mission built into it.

So while getting Phoenix was important immediately, content was built around the idea of having them long term. First Order will be no different, and I suspect Resistance will similarly be useful going forward. Take this event not as an unfair release of a character you can't get (honestly, it's not fun if you can get every character 7* right away, without working, IMHO), but as a warning that First Order stuff is coming, and so is Resistance stuff.