The main advantage I would think that is not mentioned is mitigating the price of real estate in expensive regions like Hong Kong, New York, San Francisco etc.
I came here to say the same. Cities with expensive real estate are often the cities where latency matters even more. This is essentially a datacenter that can be dropped in the ocean, rent-free.
Regarding real estate - what entity owns the portion of the sea where the data center is located? Is there security? Curious how this would work in terms of property law.