Take that with a grain of salt- the numbers they quote in that article are based on incredibly vague criteria. What exactly is this "benefit to mankind" dollar value base on?
As for the food fish v. aquarium fish- different species serve each purpose, and food fish collection won't necessarily preclude ornamental fish collection. Beyond that, ornamental fish collection requires skills and infrastructure that may not be present in many reef locations.
The only thing that you can take from that piece is that coral reefs and mangroves are good things, though the included data do nothing to prove that point if examined with any level of scrutiny.