Corsairs are not there to "protect" exactly. The Zoners gave the Corsairs the routes through 49 and safety and access to the system to stop people from finding the system. The whole idea is that if the Bretonians or Mollies had found out about the system they would obviously sweep right in and take it from the Zoners, with little the Zoners could do about it. So, the Zoners bring in the Corsairs to keep the Bretonians and Mollies occupied and not bothering with 49. It does fit right in with the Zoner mentality, dont get into the confrontation with the Bretonians or Mollies, instead throw one of their enemies at them so you dont have to deal with them.
Now, as to the NPC, I couldnt care less about how many or how strong, except there really shouldnt be molly NPC's as that is the whole reason the Corsairs are there.
Yes, Gran Canaria is "owned" by the Zoners, but does that mean you should ignore all the rp issues that come along with a huge non zoner population living there?