Do you even help the survivors that are fighting Demolishers?
They're usually 3 against 1 of these big Goliaths, and a couple of spitter zombies too, and the survivors get absolutely wrecked. I've killed a couple of Demolishers in the Old Town, but I always end up using my firearms to break their armor, so i can kill them more effectively.
I usually spend all my ammo, or at least a lot of it, and the sound always attracts virals, which is even more annoying. So I just stopped helping those survivors because it's not worth it... in-game at least.
I spend alot of ressources killing the things, so I just gave up.
Do you ever kill them outside of that boss fight where Raïs takes away all of your stuff?