That's not my argument at all. After all, it's obvious the whole server can't participate in the liberation of ONE captive and the whole server can't participate in the 6 man bc that fights for the AC. My argument is if people don't want to participate in besieged, let every npc get captured, and not bother to rescue them, players shouldn't expect to have access to the services they provide. It's that simple. Getting a captive back isn't hard, it just takes some legwork.
If one person could prevent them being captured, I might be inclined to agree. As is, the general apathy toward Beseiged as a broken event basically translates to a punishment to those who need a given NPC that isn't present, not so much a reward for participation. No other job literally loses its chance to acquire its abilities as a result of same game event, and I'd probably argue that COR dice are also too expensive on top of this inconvenience. Fortunately a lot of Empyrean head gear replaces the Turban as a TP piece, but not all jobs are that lucky.

Frankly, I'd nix the true sight mobs and the need for keys or other people to get around in the beastmen areas. You're definitely best of being a THF to free prisoners since you won't need to farm individual keys, but even then you could waste hours searching a specific zone for a specific NPC just to find he was in the other.

Generically, they should probably get auto-freed every conquest tally. As an alternative to punishing players, if the NPC related to COR dice is taken, the dice will still be sold, but at 2x the price, citing "difficulties" in procurement with said NPC absent so cost is at a premium. Meanwhile, for the Turban, the value of bronze could be devalued to 3 equaling 1 if the NPC were present. Or maybe needing silver instead.