I didn't think this was about what the player said, but instead about Blizzard leveraging their influence to shut someone up. I think that'd be wrong even if the player had said something "bad".
Now that I think about it, for most people it seems to simply be an issue of good vs bad.
It wasn't just Activision-Blizzard banning Blitzchung and confiscating his prize money. The official Hearthstone account on Weibo also parroted the Chinese government party line, "We will, as always, resolutely safeguard the country’s dignity" in Chinese.
Like if they said, in America, "Of course, USA #1, never forget 9/11, freedom baby", that would just be more boilerplate pandering and not really political.
Is the level of hostility that high that even such sweet nothings are treason?
Now that I think about it, for most people it seems to simply be an issue of good vs bad.
Maybe I expected too much of them.