To that I could reply that this isn't a gun so the barrel is strictly needed otherwise you are mostly cooking your own crew. But more importantly this is an important mechanic of the ship: it is disproportionately strong, but unlike all other ships (except the Khalkotauroi, but that one work the same way) you can permanently disable its firepower for the battle. If the main gun could still fire after the barrel's destruction, there would be almost no point to destroy it rather than target the main hull, and it would have to be severely nerfed.
Sorry but that's a core element of the ship's design and I won't change it.