The best counter to the Maquis rhetoric is that the Federation could always wash its hands of the DMZ and forbid Starfleet from interfering and if the Maquis provoked the Cardassians to wiping them out, the Federation Council might reverse the policy, though it could be too late. The real alternative is a war and remembering from the incident with the Phoenix, the admiral told Picard that Starfleet was still stretched too thin after Wolf 359 and they had to avoid full scale conflict at any cost. Even if Starfleet wanted to, they were in no position and the Cardassians were never more than a regional threat, so it's not like the defense posture at the Romulan border could be drawn from.