There have been a lot of inRP situations of pirates being a thorn in their sides. Remember the Indians? Or people like Altegra and Ciplian? And as said, it's just a test for now. It was even requested by Altejago a year ago already.
The new "Liberty Pirates" who work for the Rogues will now have to use Rogue or Hacker IDs then. One can't have it all. And especially in Liberty it's very hard to deal with indpendent pirates anyways. I don't see a problem why one who likes to RP a pirate in Liberty, can't use a Rogue ID.