Actually, Corsair-Zoner relations are not as simple as "Neutral", "semi-allied", "semi-hostile" or w/e. Zoners have no centralised diplomacy.
True, Corsairs look upon Freeport 9 with greed, due to the biodomes that they would love to claim, and on Freeport 5 with annoyance as it is used by Bounty Hunters.
But they also live on Gran Canaria. Freeport 11 is a useful base out in Delta, and I'm sure they appreciate the efforts of hired guns operating out of Freeport 10.
Zoner neutrality is not maintained by "keep away or die" capfleets, but by the fact that Zoners offer services that are necessary to the survival...of everyone.
You don't see Hunters taking a hostile attitude towards Zoners just because they supply the Corsairs with food, and you don't see Corsairs taking a hostile stance because they grant docking rights to those same Hunters.
As for Zoners pulling together to form a "house"...that is the very thing that would not happen. They are an eclectic mix of individuals who chose to live by themselves with no higher authority. "Zoner" is really more of a tag for "I don't want to join a faction" than an "organization" in it's own right.