Yes, it didn't make sense, but you never know with Marvel. They might decide to change things up. It would've been in the same way as Jim Phelps suddenly becoming a villain in the first Mission Impossible movie, even though he was an incorruptible hero through and through during the series. They might've just thought it would've been cool to have the new Ant-Man fighting the original Ant-Man. It would've been such a middle finger to the character though.