And we can't take control of the system from the NPC faction that is also there, so it's not our system.
Technically, if you are native to the system, it's your system.
Being in control is a different story - but your faction is in there and you can support it or abandon it.
It would not be the first time when people dont like the neighborhood and abandon their newly placed PMF...
(There was rather recently case when a PMF was inserted in a system where local owners (non-pmf) were actively supported by a player group bigger than the supporters of the new PMF)