Well, it depends on what kind of gatlings he is producing. If the planet is neutral, right now he's making gatlings that are friendly to you. But as soon as you take it, he'll start churning out ones that will go attack your home planet. The odds of a loss with that -- while trying to use a superterminal, no less -- are pretty high. If you capture it just briefly, you should be able to get those fabricators. If you don't capture it, but just clear the planet, then the dyson gatlings might help you out, instead (not against core ships, though).