Yes and for all we know the octopus prefers to live in a place safe from predators, always has lots of food, and a veterinarian on call when it gets sick.
It's strange to me that people anthropomorphize animals to make big claims about the animal wanting to live in the wild. If you release that animal into the wild it will likely be eaten or starve but everyone assumes the animal wants that based on absolutely nothing.
Why not anthropomorphize animals under the assumption they would want a life similar to what we've built for ourselves? Is the validity of the complete guesses about what an animal wants gain merit based on how holier than thou the people making the guesses are acting about it?
Bottom line, the octopus is safer living in an aquarium with ample food than living in an environment amongst predators where food is scarce. All animals have a strong survival instinct (they'd be extinct if they didn't) so it's more likely if an animal could communicate it's preferences, it would choose the option where it's most likely to survive for a very long time, so it would choose living in an aquarium.
If a I scream "RELEASING ANIMALS INTO THE WILD IS MURDER!!!!!!" over and over again, does that make it a more compelling argument?
It could also hide from predators in an aquarium where it will be brought food every day and get medicine from a veterinarian if it gets sick. An Aquarium is the safest place for the octopus to live, so why wouldn't it's survival instinct tell it to live there to hide from predators?
We should set up an experiment with an aquarium that allows the octopus access to the ocean. Do you really think the Octopus would run away from the aquarium where it's safe from predators and gets fed every day?