Well, luckily Dersu isn't an island you HAVE to go to early on, unlike Rusty Anchor (probably). You can likely just clear out Tekron, Monter/Verona and maybe even umkas, and when you get back to dersu the pirate won't be a problem.

Also, try DG's suggestion of pausing the game during the loading screen. You may get to at least chug a rage potion or something before the fight.