Because maybe someone on the dev team likes Gill? There doesn't need to be a logical reason for choosing Gill specifically -- I just wouldn't be surprised to see a Street Fighter villain, and we know that Gill very nearly made the cut for the previous MvC. He's also not playable in SFV (yet), and his inclusion would help differentiate the two rosters.So why wouldn't they just add M. Bison who's been higher on the polls for years?