So you think the Chinese government's motivation for protectionism is purely because they are undemocratic evil-doers hell-bent on preserving their power.
I disagree and believe they have other motivations behind protectionism, limiting democracy, and authoritarianism.
It seems you probably don't have background in Chinese history. There was a period pre-WWII where China was divvied up by colonial powers and humiliated in defeats for over a century (primarily due to a weak navy). The country was addicted at that time not to Facebook but to opium, which was imposed upon by foreign influence. Both nationalist and communist parties recognized this and vowed to unify and expel foreign power. The communists ended up essentially winning, but the legacy of weariness towards foreign influence persisted.
I can assure you the #1 and #2 things in China's mind when banning facebook and google are to #1 prevent a backdoor for the US into massive data collection and #2 nurture homegrown technology companies to prevent spilling wealth out. You might consider #2 to be unfair, but you'd also have to consider that the US was a fully developed economy, and China's developing economy would not be fairly competing against foreign tech companies. The decision has nothing to do with free speech as facebook would simply have to comply with local laws and would have gladly censored at the request of China—but that wasn't the issue.
That being said, protectionism isn't exclusive to China. It's adopted heavily in Japan too, as well as in the US. You can't really argue for or against it as it's a matter of sovereign policy as foreign citizens do not have a natural right to exploit a sovereign market.
Regarding democracy and authoritarianism, keep in mind the the country was super poor and uneducated. Ceding power democratically across the country would have probably resulted in massive corruption. The country is not a dictatorship though, but it is governed by a subset of the population who are communist party members. While they probably want to keep power to themselves, they'll also in theory be better governors than the general public.
Believe it or not the population of China overwhelmingly supports their government. The authority and legitimacy of a government does not come from democracy per se (nor from opinions of people half-way around the world), but from the people. Democracy is a great way to represent the power of the people, but as long as the population approves and delegates power to the government (by not rebelling), then it has legitimacy.
So no there's no democracy, but if they did have a vote right now the people would side with their government, and not the poorly informed foreign distant opinions from people like yourself. It just so happens their form of government does not delegate decisions of governance at the same granularity to the people as we do in America, but then again we don't have much granularity either through our representative form of government (we don't even pick the president!).
They pick their premier through rules of the communist party. We pick our president through a set of complex rules masking the fact that an electoral college actually selects the president (with things like super-delegates, which were enacted to reduce the power of the average voter since one election the democratically elected candidate didn't satisfy the DNC party expectations). In the end they have one party, we have only two real parties. There's not much difference except we directly elect a few more representatives than they do.