I tried soloing Sir Lucan on red and no matter where you aggro him, Guard Doolin shouts that I don't belong in Freeport and aggros.
This isn't classic at all.
Sir Lucan D'Lere could be isolated from the other guards by simply pulling him to the zone, snaring him, and zoning, OR, just zoning and having someone Non-KOS hail him while the rest of the guards walked back to town.
Currently, Sir Lucan, even if he's alone at the zoneline, will cause Doolin back in freeport to aggro, which then brings all the other gatehouse guards, including the newbie guards at the entrance who are magic immune and hit like trucks.
There's no mention of Doolin ever being a tether for Sir Lucan.