PO boxes are not an address so google maps won't be able to tell you where it is. Whatever google maps is showing you is wrong because the PO box is in a post office, not a country club.
Finding the actual location of a PO Box is pretty simple though since you can just go the USPS website and type in the zip code of the PO Box and it will give you the nearest post office. Fortunately for you there is only one post office in the zip code 97401 that offers PO boxes so it should be pretty easy for you. Get to it.
But why do you care where is PO box is anyway? Are you going to camp out there and try and photograph him or something?
EDIT: The post office is nowhere to be seen in that screenshot, so you were off.
