Don't they use "Metro" to refer to the greater Fredericksburg Metropolitain Census Area? I ask, because iirc the DC cops/firefighters are still under that unconstitutional rule requiring them to live inside the DC borders.
As for holding a trespasser at gunpoint until the "real" cops arrived - in Virginia there have been several people sent away for life for that exact crime of armed kidnapping. Even if the shmuck is not charged criminally he could face a nasty civil suit once his erst-while guest sobers up and talks to an attorney.
In any case, unless he's a Spotsy. Co. deputy he was out of his jurisdiction and only has the powers of citizen's arrest, if I remember the case of the off-duty Petersburg cop who chased the drunk drver into some preacher's car.