In a recent game against a Special Forces Captain, I noticed that the SFC's first bonus ship was the Sentinel Frigate, yet the frigates did not patrol from their special forces posts.
Approximately one hour into the game, I saw plenty of fighters, bombers, missile frigates, and other ships arriving in random wormholes, and could see them moving around in scouted enemy systems, but sentinel frigates at special forces posts never move.
Relatedly, once sentinel frigates do reach a player-controlled system, they tend to stay in one place by the wormhole - which means they get shot at by wormhole turret defenses even though, as tractor-immune ships, they could easily move away. AI sentinel frigates should probably evade enemy ships the way that snipers do.