As a matter of fact, Nothing!. China did nothing wrong. There was no way anyone could have predicted a virus oozing out of a 315 billion tonne piece of ice. The only problem with China is, they just end up being on the wrong side of things every time. China seems to be breeding ground for all types of ancient viruses, bacterias and fungi.
Even a type of Meliola Anfracta was found in China a few years ago.
Meliola zangii, species of fungus in the family Meliolaceae that was found in China. It was described as new to science in 2003 by Bin Song. The fungus grows on the plant in the form of black, velvety spots up to 3 mm in diameter. The perithecia are spherical and black, and up to 150 µm in diameter.