...Or perhaps some of them (chiefly, Gosheven) were convinced that their inevitable deaths would be beneficial to their ideals, and possibly to the greater good of mankind, while leaving and surviving would be detrimental?
Well, I'm not going to argue about whether there are really people who think like that, because I sadly know that there are.
But I think anyone who holds this attitude is insane. There are no ideals if you are dead.
The fundamental setup in this and the Maquis setup would then be the same: forcing an evacuation would mean betrayal of the locals' ideals (with the dead/alive question a secondary concern), and Starfleet and the Federation would need to ponder the political consequences of this, especially because forced evacuation would result in the people surviving to complain, while failure to evacuate would eliminate all complaint by the double virtue of these people dying happy.
But there is a difference. The Maquis were Federation citizens. Were the Cygnians Federation citizens?