The Zoner neutrality is based on the fact that they do NOTHING, not that they trade with everybody, they simply keep bases open, each single base has its own ways, and haul supplies from Freeport to Freeport. Freeport 11 is more lenient to Corsairs than Freeport 10. Mainly because of who is near those bases... Freeport 11 has Corsairs, Freeport 10 has Outcasts.
Zoners don't get involved with house politics, they have their bases only in the independent worlds for a reason, far off from the houses, they don't get in trouble with them. Zoners wouldn't trade with ANY faction because it'd cause trouble for them in the end, they'd have to ship equal amounts of goods to each faction, to avoid pissing off another faction, keeping such strict quotas would be impossible, and damn expensive, eventually, you'd slip up, such a situation that Drake describes would occur. Well, Zoners want neutrality.. They aren't going to step up to a fight so easily, and there aren't THAT many mercenaries...
You know that the Zoners are on a knife edge with both the Outcasts and the Corsairs... The job of maintaining perfect neutrality is hard... They won't make it harder with this, since not all pirate factions are "fair" if you like.
As Duke nuke'm says, they aren't tight knit. An over all political policy of such sorts wouldn't work, they also wouldn't be able to co-ordinate such a response...
Real world solution?
Don't allow the Zoner ID to have transports, or freighters.
EDIT: To clear up one small point... The Outcasts don't NEED Freeport 10, it just helps to distribute Cardi...
