Dead orbit wanted to leave. And they were probably one of the most prepared to do so. But I'm guessing the cabal invasion showed them just how unprepared they were in that they were pretty much in the same boat as everyone else. All the factions helped out when the cabal attacked. The FWC had plans and preparations, DO had a lot of transport available, and NM provided a lot of manpower. All of the factions working together was probably a humbling experience for everyone. And that's the best answer for why they are still here that I can think of.