You're entirely incorrect. Based on what you're saying, if the brake lights burned out, you couldn't shift into gear? I've *never* seen a Ford vehicle work this way... and the number of hoopties on the street with burned out brake lights that still seem to drive around successfully would dispute your theory.
If the bulbs are shorted, this could cause odd issues depending on the electrical system design. In some vehicles, like the Super Duties, there was one circuit (two pins) on the pedal than handled both brake light illumination AND the safety interlock. I could see this causing an issue. However, that assumes the brake lights are shorted... when lightbulbs fail, they go open, not shorted.
In other Ford vehicles with 4/5 pin brake pedal switches, the safety interlock and the brake light circuit are totally separate.