I don't think anyone is opposing the concept of building an undersea cable to make profit off the communications channel. The problem is being dishonest about your motivations. In this space, Facebook has lost a lot of trust with the (widely criticized at the time) Internet.org project, and in general isn't known to be a company that really means what their press releases say.
> The problem is being dishonest about your motivations.
Having seen people work on similar problems first hand, I doubt there is any dishonesty involved. There are two groups of people involved here: investors and builders. The investors are the ones out to make money, but many of the rank and file doers that are actually doing the building genuinely believe in the good they are doing in the world. I seen't it... many times.
Heck, I've worked on such projects where I'm genuinely proud of the positive change I made in the world. Was I paid for it? Yes. Was I motivated by money? Yes. Was I also motivated by doing something good and meaningful? Yes. Being motivated by making money and doing good in the World are not mutually exclusive.
Those who wrote this blog post are very likely those whose involvement is at least partially motivated by doing good in the world.