Banning people for leaving the server during combat of any kind is stupid. Server side fixes must be here to balance this. People have lives and PCs aren't reliable. If I want to leave a movecraft battle on nations or pvping during a siege I should with the punishment being a forfiet of my ingame assets and immediate loss. Same occurs to if my PC crashes, while not my fault, balance indicates I must forfeit.
Non of the punishments should be a ban of any sort.

With this established, I will write my suggestion.

Upon a pilot leaving the server during combat, for any reason, their ship will remain piloted for 5 minutes and the ship will immediately leave DC and stop cruising. So if you leave during a region, you are instantly done for. Moreover on returning you are able to continue to pilot if not sunk (this is less important but still a nice addition).

If a pilot suicides during combat(I have written in other suggestions that pilot deaths shouldn't be allowed in combat), then the pilots ship will act the same way.

If the pilot dies the ship will automatically release, this is fair and makes sure killing pilots is not rewarded the same as a sink in any circumstance therefore making killing pilots to win points undesirable.