It was likely a pre-emptive move on Blizzard's part just to avoid any kind of controversy. In theory the Chinese government does have the power to censor them, so they could respond to pressure from groups in society and fuck Blizzard over. It being 15 years ago and everything being so much less certain back then probably contributed.
Naturally actual Chinese companies know what's up and also understand that somebody else in the Chinese government has a vested interest that they don't get fucked over by the censors.
underage labor, the bespoke solution to an economy with declining birth rates