Privateers get to Kusari the same way they get to the BMM base in Tau-23, where they base off of in many cases.
Kambei, seriously, why the heck is it any of your business whether or not the Privateers are flying heavy fighters and if they're ranked high enough to do so? Seriously, that looks like you're just fishing for things to complain about. If the BAF rules say Ensigns can't fly Paladins, but the Admiralty decided to let them do it anyway, it still would be none of your business.