No China did not. The PLA Navy would not even enter within 10 nm of Diaoyutai that it claims as its own; The PLA Navy makes its "protests" outside of the 10 nm maritime borderline.
The Chinese fishermen would love to see the Chinese coast guard vessels actually doing what you claim they do, because they just sit and watch the Korean coast guards and the Japanese coast guards detain the Chinese fishing boats in spite of the Chinese fishermen's desperate plea for help. Otherwise Korean prisons wouldn't be overflowing with 5,000 Chinese fishermen a year thrown into prison for illegal fishing.
Chinese civilians have no freedom.
Well, Beijing and Shanghai too will turn into nuclear waste lands if China decided to not honor its NFU pledge.
China can use nukes first only by being ready to see China's own cities getting nuked in return.
It doesn't even make the news unless somebody gets killed, because around 5000 Chinese fishermen are thrown into Korean prison a year.