Protests at the airport are not new to that part of the world. In the 70s and 80s the rising opposition to the then ruling KMT party in Taiwan used large scale street protests in major cities in Taiwan. Often blocking the railroad stations (sometimes even bringing rail traffic to a complete halt with thousands of people on the tracks. And the TPE airport was often brought to temporary closure as they blocked all access to the airport.
Taiwan riot police were very busy in those days with the infamous yellow riot control (essentially crash tenders) trucks in use everywhere.
These protests only ended when the opposition DPP party came to power. The current President of Taiwan is from the DPP and her party may currently be the majority in government.
The KMT controlled government of Taiwan in those days , under the direction of Chiang Ching Kuo (son of the late Generalissimo Chiang Kai shek) took a benign attitude and did not release the military on the rioters, which allowed the eventual ascension of the opposition party. IF the KMT had resorted to it's old ways (228 incident) many thousands would have died.
A lot of people were bloodied in those riots in Taiwan but if I recall correctly (I lived in Taiwan in those decades) nobody was killed although many rioters as well as riot control policemen were sent to the hospital.
I watched one early morning in Taipei in the late 70s as Taiwan riot police were practicing riot control and right behind them were the military with guns. But the military was never used (never made an appearance in any riots) and the riot police were ordered not to use violent force, other than the yellow water trucks and batons. Riot police never carried guns.
The problem is that the HK rioters are facing the CCP government of China. Which is a different animal entirely. The CCP faces dissent from Tibet and Mongolia, the problems with integration of HK and the Taiwan issue. They are likely to take a very heavy hand. They will not allow HK independence because to do so will be to allow TAiwan Independence as well as Tibet and Mongolia independence. The CCP will fight tooth and claw to retain it's control of China.
IF protests disrupt the society in HK to the point where the airport can not open and function and HK itself is brought to a standstill I can see the CCP government of China responding with force.