Blizzard decided that "free hong kong" was:

"Engaging in any act that, in Blizzard’s sole discretion, brings you into public disrepute, offends a portion or group of the public, or otherwise damages Blizzard image"

I suppose what is offensive is always up for debate, but I don't see any reason there wouldn't be consequences from folks who live in a free society when they see such a light level of speech clamped down on, presumably because on oppressive regime wanted them to.