There are a (very) few people who would expect to be able to reach me relatively quickly in an emergency unless I told them I was going to be off the grid or at least intermittently available for a few weeks. I don't think that's either unusual or unreasonable.

Not unusual, but it seems like you would want to be contacted in an emergency. So it's a good thing that cruise ships will be getting great internet service. You still have the choice to ignore non-emergency calls and only take emergency calls.

Maybe? If I'm in the middle of the Atlantic and can't do anything maybe not. In any case, I'd be reasonably confident that regular satellite communications today would get a regular emergency message through assuming someone knows what ship you're on.