Your cruel AI shot the base with tree or four Novas at once, of course that will bust the pirate base. The pirate base is a regular dead asteroid with some boni, one of them are the 6000 HP without having to upgrade. Amongst other stuff I made a thread some time back about how the pirate base needs a planetary shield to better withstand this kind of spam, especially since AIs tend to focus-fire on pirate bases, for whatever reason.
Maybe I missed to watch a hit then, well still 2 shot.
Pirates need some countermeasure against farming titans soon... they aren't really threatening any more, most people seem to be happy to have their titan fed...