I'm saying it's a risk, and directly responding to the notion that "for now" emigration is at-will.

Human trafficking is a risk in any scenario, though. It's unclear why that's a salient issue here.

It's salient because seasteads are relatively lawless and, like Alcatraz or a cruise ship, difficult to flee without assistance.

I'm glad you brought up cruise ships because, as you say, they are difficult to flee, and they have indeed been embroiled in human trafficking. Few people think that this means that cruise ships are inherently a bad idea; it just means that they should be done well. Why do you think seasteading can't be done well?