If the (plot) cards fall right, however, Barregos could simply declare his systems as non-combatants that refuse to follow the Mandarin's illegal orders and then be "broadcasting" that to any ships coming "in system" and then have his ship posture OR fight according to an arriving set of ships' responses to that broadcast.
Obviously the GA is going to respect Maya's status, creating a de facto "smaller successor state" under Barregos and Rozak, and for anyone else? well, the bull has horns.
The problem with the view of these nice and successful Maya succession scenarios you have described is that in Torch of Freedom (i think) we have a few excepts between story sections of a future Honerverse "in-universe" book called
'Origins of the Maya Crisis' supposedly describing what happened there and the events leading up to its succession from the League.
Given the numerous other monumental historic events playing out all around the galaxy, i think the implications are that The Sepoy Option and Barregos actions are certainly going to make some serious ripples somehow and somewhere. Given that we have also have going on:
1) The fallout of Second Manticore
2) The confrontation between Tsang, and Manticore/Beowulf at the Junction
3) Beowulfs isolation and declaration of Succession from the League
4) The first "spontaneous" uprisings in the Shell and Verge
5) Rampajets Suicide
6) The Mass Bombings, Seccie Uprising's, and Occupation of Mesa
7) The Grand Alliance's first true military offensives
8) The preparations for the launch of the Renaissance Factor
This makes the fact that a single comparatively wealthy and successful Frontier Sector suddenly decides to go independent seem fairly small fry. Given that "Crisis" will eventually (in a century or so) be used to describe it, that implies it set off or was involved in some fairly major historic incidents. These have been a variety of things so ill list some I have thought up:
A) Maya inspired other or neighboring star systems to also make a break from the League, acting as the first pebble in a landslide.
B) A massive battle took place at some point, either to reclaim the sector or for them to repel/survive reoccupation.
C) The Sepoy Option somehow failed and everyone at last saw the depths BF/FF were willing to go.
D) Maya became its own independent and successful kingdom/republic and lead to future breakouts from an already shaken and broken League.
E) Education and Information decides its easier to throw blame locally and does to Maya what it is currently doing the Beowulf, painting an otherwise bloodless coup as a massive black treachery.
F) The events in Maya are otherwise fairly mild but coincides with other more serious events and so gets tarred with the same brush.