A Brexiteers oversimplification of the issues.
Brexit provides a huge strategic gain for Spain over Gibraltar, for a number of reasons.
If you want to inform yourself, I suggest you do some research.
Not least is who controls Gibraltar airport. Spain argue it is on Spanish land.
And then there is the border.
Gibraltar is not in the customs union but it is in the Single Market. Big potential problems for the many workers who cross the border everyday.
Gibraltar doesn't have sufficient accomodation for all its workers, many thousands come from Spain everyday.
Spain has far more leverage over Gibraltar than UK
Guess what Spain has taken back control.