The maquis were often referred to as being federation citizens.
And they were never referred to as NOT being federation citizens (if there are examples to the contrary, now would be the time to post them).
Yes - the federation treated its DMZ colonists as disposable assets with no rights, but it claimed they have obligations only federation citizens are bound to.
As for the DMZ - you can draw a line in the middle and claim half is cardassian and half federation. If none of the two powers can station troops in the DMZ, the territory is not really cardassian nor federation. It can be safely referred to as being a no-mans-land, neutral territory, etc - which is why it was referred to in this manner.
I thought the people living on Dorvan had to give up their citizenship (maybe I'm remembering wrong).
There is compelling evidence that Dorvan V lies beyond the DMZ, in cardassian territory proper:
The cardassians were bringing military assets on that planet (which would have been a clear violation of the treaty, were it in the dmz) and Picard&co, far from claiming treaty violation, never even pretended it was not within the cardassians' rights to do so.
The cardassians seemed to have the legal right to forcibly evacuate the federation settlers - which they would not have had, were the planet in the DMZ.
So do you agree that it was wrong for Starfleet to side with the CU and harass the Maquis whereas neither Starfleet nor the CU seemed to take much significant action against Cardassian offenders, such as The True Way? I'm still puzzled over whether the Maquis formed to essentially do Starfleet's job and preserve their own safety in the DMZ OR whether the Maquis were a paramilitary aggressors who tried to drive out all Cardassians illegally.
The morality of the maquis' actions is debatable - there are good arguments supporting both sides - terrorists or freedom fighters.
Usually, in such situations, history - the winner - decides what version will make it into the history books.
PS - However, as I already mentioned, the federation's behaviour towards the DMZ settlers is inexcusable:
"The federation betrayed the colonists' fundamental right of property when it ceded their colonies/lands to the cardassians, in an attempt to appease the cardassians.
The federation further betrayed the colonists - still federation citizens - when it hunted them down like animals - killing them without trial, poisoning their colonies with biological weapons - with no repercursions for the perpetrators of these crimes (starfleet officers).
But the greatest betrayal the federation perpetrated against the colonists was when it didn't lift a finger to save them while they were massascred - ALL of them: WOMEN, CHILDREN, ELDERLY (non-combatants) - by the cardassians/dominion.
Apparently, the colonists are federation citizens only when it's convenient for the federation (being bound by federation treaties and the maquis branded as terrorists), NOT when the federation has obligations to fulfill toward the colonists - such as protecting them against genocide.
And why this second-class citizens treatment?
Because the colonists dared say no to big brother - from that moment on, the colonists were just expendable cannon fodder for the federation, without rights, only with obligations, to be disposed of at its convenience. "