I think there is at lear ONE clue to that. Wolverine KNOWS the older version of Quicksilver. That would make more sense if Quicksilver was, in fact, his pal from the Alpha Flight. (BTW, they blew up the chance of including the Alpha Flight - Tyrion could've been a terrific Puck, heh heh!) Northstar is, at least in old 616-Marvel canon, FASTER than Quicksilver and able to reach near-lightspeed - a thing that Quicksiver cannot do. But that's a technicality. Oh, and just like Quicksilver, Northstar has a twin sister.