Hulk was not "necessarily" OORP ... however ... a pirate attacking a Junker is not smart. He would be OORP if he killed or even taxed the Junker and then chose to dock on Yanagi.
Hulk has no business in Blood Dragon turf ordering people around ... but ... if you go to New York you see indie lawfuls doing the exact same thing Hulk did. While Hulk has no authority in Chugoku ... the Blood Dragons did not take offense to him ... so the Blood Dragons must have approved. This happens in New York all the time ... LSF/SA/LPI etc allow indies to police their turf and sometimes even pat them on the back for it. And they do this to lawful traders too.
Don't feel bad ... while I despise pirates taxing allies it happens.