Its just large Pirate ships. We do not engage other ships until known to be pirates, and we will even defend other services (motherships down to vtols) in space against such if the opportunity sees fit. Dreadnought has engaged us, therefore in turn, placed on the ToSKoS.
Simplez
Like anything in life there has to be a balance, and consequences. Currently pirates are not being engaged in their activities any where near enough to discourage them. The only discouraging factor for them was the "no loot" when shooting ships down. Now however after a series of very large loots from other ships, they are seemingly well funded and enjoying the benefits of such.
Bring the balance back to " For every action, there is an equal and opposite reaction "
"Dont feed the pirates" comes to mind...
Space wars have gotten smart, there is a whole host of things going on behind the scenes. The key components , levels and skills of the mines, the gates, the drives, the pilots, the bounce points - down to the the tactics of the fights, the squadrons of fighters, the death dance of engaging motherships, the shifting of repair crew the gunner teams experience - practiced time and time again - all of these things come together to make space a truly exciting place to be right now.
ToS has always taken the offense is a form of defense route, and our passengers know that we will, on the balance of probabilities, kick pirate ass out there if we encounter them.
All ships cannot float around the universe turning a blind eye to the pirates, allowing them to gain in strength and numbers, some do have to take a stand, show them that we will fight back and we wont back down, come what may-For the sake of safe space travel across our universe.