Not only that, but the cost in both fuel and carbon emissions to move the material out further. Last I heard, the dumping spot was actually about 15 miles away from the edge of the reef, not the actual reef itself. This combined with the fact that when we’re dealing with volumes the size of the ocean 3Mm^3 isn’t that much volume at all (considering that the reef is 344,000 km^2 in area).
Also I trust the WWF about as far as I can throw them. They do have a tendency to try and twist facts and manipulate headlines so they get more press and try to throw fervor over events they don’t like or go against their political or ideological agenda.
While I wholeheartedly agree that the reef needs to be protected, and I personally would not want to see a coal shipping port expanded, but that port is being expanded regardless of my opinion. At this point I’d rather them dump it closer inland than bardging it long distances and spewing all that carbon in the air.