Why is pirating on those lanes bad? The lanes aren't patrolled, and all of them have a debris field to retreat to in case lawfuls come (RP).
Does that mean pirates can't pirate on the Planet New Berlin -> Dortmund lane, "because it's a capital planet". Or how about the Planet New London -> Dublin Jump Gate lane? You can't pirate there either? Both have nearby debris / asteroid fields.
Believe it or not, lawfuls don't have complete control over their systems (apart from the Guard ones). The house capital planet itself may be heavily defended, but trade lanes aren't.