They aren't true football players,
Yea, the guy that uses his foot isn't a true football player.
The first football game was played on November 6, 1869 between Rutgers and Princeton. The game was played between two teams of 25 players each, used a round ball, and resembled a combination of rugby and soccer in its rules. The ball could not be picked up or carried, but it could be kicked or batted with the feet, hands, head or sides.
I mean, it's not like using your feet was part of the original rules of the game or anything.