GenZedong

Important to note these people technically are not CIA agents (they wouldn't get a star on Langley's wall after death) they're ASSETS. Basically Chinese who have betrayed their own people, are not formal employees of the CIA but may be paid money (including very large sums) or given/promised favors, blackmailed, or recruited to pass secrets on the basis of ideological (anti-communist) or more often personal grudge grounds (a belief they've been unfairly passed over for promotion, a belief their talents aren't recognized enough by what they see as incompetent people above them).

Still good they were shot in full view as an example but these were just recruited traitors, they received some training most likely but assuming there are no issues with supply of greedy/resentful people and no counter-espionage problems, they are the type who could be fully replaced by anyone else in their position to have access to classified or sensitive info within months instead of the years it takes for agents who are far more valuable.

Some of them may have been handlers for others and even fairly important as jumping-off points for networks of people they drew info from but I doubt they put any stars on their wall over this. (Happy to be corrected if I'm wrong but the CIA tends to use native peoples as disposable and doesn't consider them worth mourning as anything but an annoyance to having to replace their cog function in the machinery)

Rooting them out like that is good on China, as or more important is making sure replacements cannot be recruited. Unfortunately the US uses very powerful technical means of surveillance (electronic espionage, bugs, tempest attack type stuff, plus of course their vast global communications intercept net, hardware implants put into strategic network and computer devices, and advanced malware and hacking campaigns to lurk and spy) so they likely still have some great deal of insight and I personally believe they're intentionally over-hyping the damage lack of human-int sources in China has had on intelligence gathering.. Sure it's probably had an impact, it probably limits their ability to spy on Xi and other top officials and know their movements, inner thoughts, best classified plans, etc, but I'm sure there are still plenty of holes as though Xi's anti-corruption drive has been tough and thorough I doubt it's gotten all the rats.

What they may be really upset about is their ability to have chances to color revolution/coup China by using insiders they control has greatly diminished. And that was always the highest threat of these types. CIA maneuvering to get liberal counter-revolutionaries into high party positions and to steer the country to letting go of the commanding heights, to allowing more liberalization, to letting western propaganda in, to making missteps, etc which over time would rot at the foundations and lead to a crisis that could be exploited as happened with Yeltsin.