How did Captain Hook get out of Storybrooke in 2x15?

I think that only applied to people who'd been affected Von the curse. Hook arrived in Storybrooke after the curse had been lifted, he wasn't one of the original inhabitants, so it didn't affect him. I think that's also how Emma and Henry were able to leave with no problem; Emma was transported out of FTL before the curse hit, and Henry was born in the real world.