... but capital ships are actually less of a threat for pirates than fighters, with only one exception ... gunboats (especially those with lots of missiles). Anything bigger you can shake easily in debris fields, unless you're flying a lone pirate gunboat. In that case the pirate is screwed anyway and deserves a capship response.
Also I'd say a major portion of pirates focuses on fighting the lawful forces, which should be the neccessary evil, not a goal.
I fully support the LN on this one. If there are any stranded, liberty-banished capital ships without support, they are easy target for pirates. Also some of the Xenos or Phantoms might help you make this happen ... I think. So it's a civil war you can win.