Pirates are controlled by the AI, so a human has no problem with them. The only thing I have to add to Darvin is that it's very easy to not even have to fight the pirates. All a person has to do is figure out which planet of his is closest to the pirate base. On that planet, build a repair bay and say 3-8 turrets and the planet is defended. The pirates attack turrets by default.
Pirates are told to chase colony frigs and trade ships ( the latter is the more effective, requires no effort ) by default. If a person has tradeports up, he doesn't even have to build defences. The pirates will chase the trade ships indefinitely.
The idea is nice in principle. So far the implementation could use a slight fix.