Hiring a uniformed police officer as a personal body guard would also mean that my bodyguard would be free from any assault (it would carry the penalty of assaulting an officer, even though he was not "on duty").
We have had situations in our state with our governor using state troopers as personal security. He has even used them in intimidating situations where he has verbally threatened private citizens.
Plus he/she also gets a pass from fellow cops as they all give each other a break.