Capital ships that have lost their main guns (or sustained heavy internal damage. I have been unable to get the precise circumstances) will almost always turn to keep one side facing the player, and will float around almost randomly, even if they still have engine power. They should attempt to retreat (towards the nearest friendly[from their perspective], nebula or gate, and maybe try to keep the damaged sides of their armor away from the thing that's shooting at them.

This is most noticeable on the Phobos dreanought, due to the massive HP pool and relative ease of knocking out the guns with certain weapons (eg. Dvalin Ion9).

If having capships get disabled is supposed to be a thing that happens, then drive compartments should be made to not kill the ship, and have the ship lose all drive capacity when it's destroyed, rather than the current "reset the drive when hit" system. However, this would require some form of built-in compartment regen or damage repair ability to prevent players assembling zoos (it will happen).