Gameplay matters more than fluff, and $$ matters even more than gameplay. FFG will be happy to release these pilots in whatever they fly in whatever book or comic in whatever bonus expansion they release at a future date. There was no reason to not use full canon characters as the pilots for a ship which has no known named pilots. It's simple really- They needed named pilots for the ARC, they found some from recent sources they could reasonably believe flew them at one point, and they slapped them on there.
And when they slap them in a Y-wing and an A-wing a couple years from now, we will buy that too.
And either way, I'm getting to the point where I just make up my own X-wing miniatures game canon anyways. This is a minor, minor fluff issue when you consider Biggs flying with K-wings and E-wings or Poe and Snap flying next to their 20 year younger mothers.