As someone who has eaten live octopus (though "dying" at the time) it's not that big a deal. It's no different than eating it already dead except the suckers stick to the sides of your mouth a bit.
For those that get indignant about eating such things, I say if you're not a vegan then you're just being a hypocrite. Different cultures eat different things in different ways. I've been fortunate enough to experience many cultures different than my own and I'm always impressed with food. Dogs, cats, horses, rats, octopus, whatever. We are the top of the food chain, and like it or not, that's part of the natural order of things.
Now, talking about how we over farm, over fish, or whatever is another subject, but just complaining that someone eats something you or I find distasteful is not likely to win you a lot of friends in an international forum like this one.