It's being added for all bases helps for gangs attacking or defending.
For defenders it means a little bit of time to get set up when they take the base before the attackers start coming in.
For attackers it means when they kill a defender, the person they just killed doesn't run in and kill them back after 3 seconds when you (the attacker) is now at less health.
The changes are being made to facilitate basing in the future when there would be more gangs participating.
Also like to note that gang ally protection in bases has now been disabled.