If he does allow it, make sure you are officially covered as security, etc... for liability reasons. If not, you're just a "citizen" with a handgun...liable for your own actions. (technically...we are always liable for our actions...that's why cops get jacked up in the courts frequently over shootings....someone like Kim Worthy loves the opportunity to press charges on a cop.)
Note: someone please correct me if I am wrong with this assessment.