Update: Blizzard subreddit moderator PwnBuddy has posted a megathread on the "Blitzchung Situation", where they also explain why the subreddit was locked. Apparently, it was the work of a single mod who also deleted their account, not an attempt to put a stop to criticism of Blizzard.
"For some reason, one of our recent mods set the subreddit to private then deleted his account," the post reads. "It was an odd event, but rest assured, us remaining mods have restored it to public. No, we were not contacted by Blizzard, nor are we employees to any extent. We are committed to supporting this community."
All discussion of Blizzard banning the Hearthstone Grandmaster after his comments on Hong Kong has to go in the megathread, say the mods, but it's taken over the subreddit all the same. Every single top post is calling Blizzard out and stoking the fires of the Blizzard boycott.
Update: The Blizzard subreddit is once again open to the public, and a quick glance at the recent thread titles provides a pretty good idea about why it was closed in the first place. I wouldn't be at all surprised to see it made private again before long—I'll update again if that happens.
The blowback from Blizzard's extremely heavy-handed reaction to Hearthstone Grandmaster Chung 'blitzchung' Ng Wai's call for freedom for Hong Kong yesterday—removal from Grandmasters, a year-long suspension from all competition, loss of all season two winnings, and the effective firing of the two casters involved—has come unexpectedly fast and furious. Fans and players are pledging to boycott Hearthstone and other Blizzard games in response, and earlier today the Blizzard subreddit was made private, meaning that it can only be accessed by people specifically invited by the moderators.
The lockdown came without warning or explanation, but this message from r/wow moderator DotkasFlughoernchen all but confirms that the outrage over Blitzchung's suspension and loss of winnings is the cause. "[The suspension], naturally, has sparked a lot of... let's call it 'discussion.' As of writing this it's the top thread on r/worldnews, r/gaming, r/hearthstone as well as other Blizzard subreddits including r/overwatch, r/starcraft, r/heroesofthestorm and r/warcraft3," they wrote. "It also makes up nearly the entire frontpage of r/Blizzard."
To be clear, this likely isn't a matter of Blizzard clamping down on conversation, but it does speak to the volume and ferocity of the backlash. As redditor Ghend pointed out, Reddit can be rowdy: "I would hazard a guess they were having to spend a lot of time removing things like death threats and threads that did nothing except spam the slogan of the protests, because that's what redditors like to do," they wrote.
Evidence of that can also be seen on Blizzard's own forums. This thread in the Hearthstone forum is already well over 500 posts, but lively discussions are also underway on the World of Warcraft and Overwatch forums. (More pointed, and much less polite, criticisms are also popping up here and there, but they tend not to stay around for very long.)
Officially sanctioned or not, the clampdown won't do anything to change the perception that Blizzard is cracking down on free speech—ironic, given that it was a call for freedom that sparked this furor in the first place. I've reached out to the r/blizzard moderators for more information, and will update if I receive a reply.