I will put this in simple and hopefully uncontroversial terms:
Gallia, the Royalists to be specific, had the task of providing a big bad boogeyman in the Taus and it's wonderfully accomplished this task for the better part of a decade, but now that it's been utterly crushed and the Council will most likely take over the Gallic Core Worlds, there is no point anymore in its existence. It's outlived its purpose and to forcefully keep it alive as a microstate is to keep it redundant and essentially useless in the grand scheme of things.
It's clear that Bretonia will not attack Edinburgh and neither will Crayter or anyone in the neighbourhood, nobody's getting in and nobody's coming out, the only activity that could keep its players busy is fighting Gaians in the system and I don't have to mention how denaturalizing that is to both.
A GRN stuck in a single system with no way of returning home is unrecognizable as a GRN, its task, its reason to be, is to fucking crush everything in its path and generally be a pain in everyone's bum and if it doesn't it's just not the GRN, and the Gaians have been artificially relegated to unlawful BAF for almost as much time as the length of this narrative ark and to force them to keep this role further is to essentially kill them.
So, really, why?