It's A PERSONAL FAILING NOT INSTITUTIONAL FAILURE. Qin Gang SUCCUMBED to his inner demons/desire/lust/love for the woman which resulted of him fathering a child in the U.S.
I don't know how that can be read as "HIGH-LEVEL OFFICIALS ARE TOO AFRAID TO DEFEND NATIONAL INTEREST" when the man has been essentially fired from his position that he has been working so hard to attain.
It's quite worrying but understandable to a certain degree why the virulent Chinese nationalist such as yourself would find Qin Gangs action as an emblematic and a symptom of perceived betrayal/treasonous actions by important officials in the CPC. What actions should have been taken by the leadership that would pacify and satisfy the angst, accusations from your side? War over Taiwan during the Pelosi visit? For what? I am sorry to disagree with you but I for one am glad that Chinese leadership as imperfect and as human as they are just like the rest of us, they do not succumb to emotional barking and actions that would have caused irreparable damage to China's aspirations of achieving economic revitalization and military power. If your country was a democracy like India, then in my opinion there's no doubt that China would have invaded and have taken military actions against Taiwan and India many moons ago to the detriment of China.
I agree on most things you say but on this you are very wrong.
First, senior public officials have no right to a personal life. This is largely a modern (western) concept. If you are secretly having an affair, are homosexual or anything else that needs to be kept private you are a liability. Foreign intelligence agencies will be monitoring everything you do and will use it against you. As well as the obvious blackmail, what if the Americans offered him something like a university place for his son in return for a favour?
As well as the public security threat, there is the moral failure. Even if there were no foreign agencies combing over your every move, having people who succumb to their inner demons sets a bad precedent and is a very slippery slope to much worse things. It's easy to overlook this, but I think the loss of morality and standards in the west is one of the biggest reasons it has failed.
For example, look at the former PM Liz Truss. She was married, then had an affair with her MP boss (causing the end of his marriage). She then had another affair with a party official who gave her a safe seat to stand in. Once in power she appointed people to power on personal terms, including appointing the black guy she was having another affair with to chancellor of the exchequer. All of these were red flags that should have lead to her being dismissed, but thanks to the modern day lack of moral standards, it was tolerated, even by the so called "Conservatives".
So no, there should be absolutely zero tolerance for this. If someone thinks that's unfair, get a regular job and they can have as many affairs as they like.