The mechanics by which you disable a player made safe zone will probably be controversial regardless of how they handle it; however from the perspective of making the game actually fun, you want to design it so that the maximum number of players, who have a stake in the fight, can participate in the fight. Ideally the attackers and defenders would agree to a time for battle, though of course they will not agree. The attackers inevitably will be the ones who initiate the process and thus will inevitably have some influence over when the battle for the fate of the station occurs.
Personally I think the process should favor the defender, and I think we should take EVE online as an example. The defender sets multiple "vulnerability periods" each week. To start the attacker destroys a specific structure that must exist at the edge of the defender's safe zone. Then during the next vulnerability period (that happens to start more than 24 hours later) the safe zone falls and the station becomes vulnerable to damage.
Disabling all damage in a safe zone seems heavy handed, but I can't think of a reason against it.
Personally I think the process should favor the defender, and I think we should take EVE online as an example. The defender sets multiple "vulnerability periods" each week. To start the attacker destroys a specific structure that must exist at the edge of the defender's safe zone. Then during the next vulnerability period (that happens to start more than 24 hours later) the safe zone falls and the station becomes vulnerable to damage.
Disabling all damage in a safe zone seems heavy handed, but I can't think of a reason against it.