If we were going to allow the othuy to be disabled, it shouldn't be something that players can flick on and off instantly. It should be something like: you start an upgrade, when the upgrade finishes the ythotha dies and there's no othuy. If you cancel the upgrade, it goes back to normal. While the upgrade is going, the ythotha can't move. (Even better if it can't move or shoot during the upgrade.) That way, a player can't just cancel the storm during the middle of a battle because they don't like where it's standing. Maybe add an "are you sure" dialog just because accidentally clicking that key would be really sad.
If we do this, the othuy should be able to kill reclaim. That would make the ythotha more interesting. Right now, since the othuy can't kill reclaim, there can be a lot left over to scoop for the defending player. Which doesn't really fit with the Seraphim mindset of "kill kill kill destroy everything." And it would be much more devastating if you snipe an ythotha while it is next to allied units/buildings.