in combination with Flux Field and shield restores from two Dunovs alternating boosts, the Kol be an invincible god.
Untrue; focus fire on it with about 100 LRM and even with maxed out adaptive shields and hoshikos repairing it, it's got about 20-30 seconds to live (depending on the exact weapons/armor upgrade levels). Maybe the Dunovs might do something, but the problem is that the Dunovs will get taken down first, and they don't get adaptive shields. While 100 LRM's may seem like a massive army, we're talking about a late-game scenario with multiple level 6+ capital ships, so it's actually something quite feasible.
If you treat any capital ship - any capital ship at all - as unkillable in multiplayer, you are going to lose it very soon, because players will take the first opportunity they see to knock it out of the game.