Actually, I believe that it's the AFRCC that monitors PLB's although the coat guard does monitor EPIRB's.

From your link:
Responsible agencies
In the U.S., offshore beacons are investigated and victims rescued by the Coast Guard. On-shore beacons are investigated by local search and rescue services in Alaska. The Air Force Rescue Coordination Center is charged with land-based emergency signals, usually dispatching volunteer members from The United States Air Force Auxiliary Civil Air Patrol. In the U.S. there are no published notification systems for other locations.