It isn't just that they can get bigger than mountain lions, the point is their attitude. They kill and eat everything though for obvious reasons they like bigger game. You don't think mountain lions and real lions or leopards or tigers are alike do you? The jaguar belongs to that same genus, and acts like it does. It is a solitary hunter which is a good thing for its prey. It doesn't congregate or cooperatively hunt like lions. It is bigger than leopards in general but smaller than lions or tigers.
Is the population able to stop the government from doing this?