In the wake of the Interloper's arrival and subsequent annihilation of the Nomai in the solar system, it seems that the anglerfish were spared the same fate. It could be due to how dimensionally corrupt Dark Bramble is that prevented ghost matter from properly dispersing throughout the interior, or perhaps the fog is too saturated with water vapor (less likely). If the Nomai wanted to evade the Interloper's exotic bomb, in this sick twist of fate, their best chance of survival would be to take refuge within Dark Bramble. But, even if they took copious amounts of resources with them to settle long term, they still wouldn't last long enough in that environment to wait out the evaporation of the ghost matter. It took roughly 280,000 years for ghost matter to even mostly fade away, so what chance do the Nomai have in any direction of survival? It'd be like having to start from square one all over again for them.