--SPOILERS--
I decided not to go along with the Doc at their compound, and free the synth, which of course meant taking out all the now hostile members of Covenant as well.
The strange thing is, the turrets at Covenant didn't turn on me, but I'm not sure whether they will activate to defend the settlement against my enemies. ALL the turrets at the compound immediately went hostile when I confronted the Doc and her goon, yet none did at the settlement.
The settlement's defense stat is also in the red at 0, despite all the Heavy Turrets still in place. I tried destroying one and putting up a new one in it's place to get the defense stat out of the red.
The result was it immediately started firing on all the other turrets in it's line of sight, and destroyed them. A regular turret mind you, destroyed 3 heavy turrets.
I reverted back to the save I made just prior to destroying the one heavy turret, but now I really don't know if they are defending the camp or not.
Can anyone solve this turret mystery? I'd rather not destroy all the heavy turrets and replace them, because it not only costs a lot of resources, it looks ugly, because the remnants of the old ones remain, and I don't think I can even place the new ones so their coverage outside the wall is as effective with the remnants in the way.