This is correct. The BOO (Brake On/Off) switch controls the shifter interlock to ensure you are stepping on the brake before you shift out of park.
The easiest way to tell whether the switch is broken or not is to simply see if the brake lights light up. Put something heavy on the pedal (a brick, etc.) if you don't have a helper handy. If they don't come on - and they should come on regardless of key position, whether the keys are inserted or not - then the switch is broken. It's about a $30 part at advance auto parts. It is located on the brake pedal arm above the part you step on.
If you put the key to position I, which is between OFF (0) and ON (II), you will be able to shift regardless of the brake pedal switch. That is the backup, so you can push/move/drive it in an emergency situation.