As much as I'd like to see old Ben as a crew card, he's already a part of the Force in this game's timeline.
So, what then, the timeline is immediately prior to the Battle of Yavin onwards? Because half the named X-wing and TIE fighter pilots died at the first Death Star and yet they're all still able to fly around with people who didn't join the Rebellion/Republic/Empire until a decade later. Half way through the first movie seems like a pretty arbitrary starting point for what's allowed and what isn't.
And that's all forgetting the fact we're getting Greedo crew in Wave 6.
Exactly.
Greedo was dead long before Obi Wan. And Luke's Gunner card was from when Obi-Wan was on board the falcon.