Thank you for raising this issue. I'll try to clarify the situation from my side.
First, there was no battle between Kritias and me yet. As usual, I contacted everyone at the processed sectors far before I have access to them. I asked Kritias to leave the sector peacefully, but he decided to stay and fight for his rooms. He explicitly agreed to be attacked. I offered him a time to prepare but he said I'm free to do it when I want.
Second, there is a simple policy for all cases like novice/respawn zone or closing sectors: if you need room, you reserve it. Devs didn't close any single room which were claimed or reserved. If you don't reserve the room, you don't need it.
Third, direct access is two-way road: now I have my newly build base being accessed by four Kritias's RCL8 rooms and two more RCL7s without an opportunity to properly fortify my new base. So it's not that uniquely who got the advantage.
Forth, to Kritias. If you think that devs made a decision that you think not fair, please feel free to drop a ticket into the support system ("Report a problem") and explain why do you think closing the sector wasn't fair to you.