How much longer does China plan to keep this event taboo?
They see what S.Korea has gone through in being a full democracy, taking lessons from it to ensure it doesn't happen there.
S.Korea is a free society now, but even as a 40 something guy, I remember days of militaristic regime holdovers from quasi dictatorship of the past.
You couldn't criticize the president, the press was closely monitored, no one dare expose rampant corruption and collusion of big business and prosecution office.
I remember my neighbor skipping classes to demonstrate against the government, throwing Molotov cocktails.
Some people got whisked away and put into labor camp, not to be seen again for months or not make it out alive.
Where is China on the timeline? They're probably currently at where Korea was in early 1970s. But they also know that the timeline now is far more compressed in modern society and change could happen much quicker.
All the the actions you're seeing from China, is done out of fear of losing grip.