It's not more ethical. It's just as bad, but the mining company decided a long time ago to smooth things out using the good old "public relations strategy". They tried to come up with something, anything, that can be seen as ethical back-up support for their operations. They tried to appeal to some vague ethics and morality, "for the people", "hear the poor", blah, blah.
Excerpts from their propaganda include (but are not limited to):
1. Mining on the sea will not displace people.[1] The mainland is already full of people. It's better for us the mining company to mine stuffs under the sea rather than forcibly relocating hundreds if not thousands of people in the long run, as an indirect consequence.
2. Mining on the sea will not disturb environment near humans[1][2]. There will be no more forests being burnt and cleared for mining ops, just to be abandoned when everything is done and the ores are sucked dry. The immediate effect of mining to human surroundings are unpleasant. Doing it on the sea makes people not aware of it every day of their lives. 824
People likes it better when there are no mining stations situated near them.[3]
3. Our mining operations are more friendly to fish and marine ecosystem in general[1][2][3] compared to it's effects to human day-to-day lives.
4. There will be no more people protesting because a mining company operating in their backyard gives them benefits that are not adequate nor proportional.[2][3] Deep sea mining is in international waters, and at most it's still no one's backyard. There are no moral ambiguity as to how our profits have to be spent. Our profits can be more freely distributed and allocated for better pursuit of mankind's happiness.
5. Oh, and just in case, we'll highlight the fact that our competitors --- who solely operate on land --- do all the negatives we mentioned above. And we'll be sure to exaggerate, just in case our point isn't clear yet.
[1] Put scientific citations here. The company publishes some sort of "study" whose conclusion agrees with the company's bottom line.
[2] Another scientific citations but from different names as to look more legit. Claim whatever you want, slightly differently phrased.
[3] Some other publications that twist the data and statistics in favor of your goals. Pepper some misleading numbers and out-of-context quotes. Slightly pop-science themed to appeal to larger general audience. 897