The original post is saying (in antagonizing language) that 30% coral coverage is a record high. If you click on the “download this report” button on the page

The original post is saying (in antagonizing language) that 30% coral coverage is a record high. If you click on the “download this report” button on the page you linked, Figures 2, 3, and 4 show graphs of coral coverage over time, support this claim. (In 1985 they were at around 30% coverage, not 100%.)