They're not really understanding octopus farming, are they?

Actually, they might understand the details of octopus farming but they’re not grasping the larger point at all. We’re told that octopi are complex, possibly sentient, beings and that farming them has certain problems. Some stemming from that sentience, some from the desired nature of their diet - other fishy things. Those technical problems may indeed be problems. But that larger point they are still missing:

But the case for octopus farming is weak, according to Jacquet and her co-authors. The main markets for the animals – the US, Europe, Japan and China – are areas where people are already well-fed. Octopuses are delicacies and do not deserve to be the focus of intensive farming.

That’s to entirely miss how product development works. Everything always does start out as a luxury - it’s that capitalist desire to profit from making more of it that drives down prices as competition enters. Mobile phones used to cost what a used car did - a good one - and air time was per minute the hourly average wage. Now they’re cheap enough that real poor people out there in the undeveloped countries have them. Leading to that famed economic growth lifting so many out of that poverty. Ford’s democratisation of the automobile came decades after the rich man’s toys.

But yes, it gets worse:

Indeed, the case in favor of octopus farming is weak. The main markets for farmed octopus—upscale outlets in Japan, South Korea, northern Mediterranean countries, the United States, China, and Australia—are largely food secure. (Food security is defined as when all people, at all times, have physical, social, and economic access to sufficient, safe, and nutritious food that meets their dietary needs and food preferences for an active and healthy life.) As consumers become increasingly concerned about animal welfare and sustainability, the case against octopus farming should only become stronger. If society decides we cannot farm octopus, it will mean relatively few people can continue to eat them. But it does not mean that food security will be undermined; it will mean only that affluent consumers will pay more for increasingly scarce, wild octopus.

Right now, the farming of octopus is constrained by the technology—it has been difficult to reliably keep animals alive through the early stages in their lives. But with further investments, research, and testing, the technology may well become available to farm octopus at an industrial scale. It is our hope that if such an option does become practical, society will recognize the serious welfare and environmental problems associated with such projects and octopus farming will be discouraged or prevented. Better still would be for governments, private companies, and academic institutions to stop investing in octopus farming now and to instead focus their efforts on achieving a truly sustainable and compassionate future for food production.

It’s not, and it shouldn’t be, society which decides such things. That is and would be the tyranny of the majority. We, the consumers, get to decide these matters on an individual basis. As with any other moral point in fact. There are those who are vegetarian, ovolactarian or not such, vegan, piscatarian, near entirely carnivorous and the most of us, omnivorous. Those who are any of these on moral grounds get to make their own choices about that sort of thing. That’s what being a liberal, living in a liberal society, means. We get to apply our ethical insights to our lives.

It’s an illiberal society that determines such behaviour for people.

That is, if an individual decides she doesn’t want to eat farmed octopus that’s just great, that’s freedom for ya’. Even that prodnoses tell us we shouldn’t eat farmed octopus is just fine - to attempt to persuade others of your ethical vision is indeed part of that liberty. But to impose a ban on even trying to farm octopusses is the imposition of one moral view upon all who may not share it.

Actually, to demand the ban is to insist that all don’t, for why ban if you think that no one will want the production anyway? To insist that the process cannot start is to insist that at least some will consume the output. Which is being illiberal, to impose ones’ own view on everyone else.

That is, as ever, the liberal polity is the free market one, where each can and does choose to consume according to their own measures and moral visions.