Proxies only work when you can directly supply them and provide them with safe haven safe from attack to stop them being totally eradicated.
Before you attack them, you have to find them. They're not walking around with foreign passports.
They're part of the local population. The Taliban's actual enemies haven't been "eradicated." They have just melted into the population, just like the Taliban did when the US arrived.
If it was that easy to root out agents and collaborators, there wouldn't be any terrorists/separatists/radicals/agents anywhere in the world. But they exist everywhere, including inside China. And Chinese agents exist inside the US. Their just not shooting at each other. But in Afghanistan, if a bomb goes off, or people go missing, that's just Tuesday. And you're not going to find who did it either. This isn't TV where the bad guy gets caught at the end of the episode. Nor is this the South China Sea where you can see your enemy a hundred miles away on radar.
Just how does the US-Indian alliance plan to achieve any of that against the Taliban in Afghanistan exactly?
Clandestine troublemaking is easy even inside an actual country, let alone a pseudo-country, which is exactly what Afghanistan is right now. It will be like this for decades, even if development starts immediately.
The Taliban's actual job has just begun. For the past 20 years they were just having fun shooting stuff and getting a ton of cash for free. Actual
governing and making progress, that's a lot harder. And I bet the Taliban will tell you that themselves if you ask them. It's been a week and they're already dealing with protests and all the multi-dimensional problems that start once you actually get power.
Without adequate support, any proxies sent in will be lambs to the slaughter against the Taliban alone. No need for China to lift a finger militarily.
You don't "send in" proxies. They're already inside. They're part of the population. That's the whole problem.
Look, if China sends in any personnel right now, there will be casualties. Which is why for now, China is not committing personnel. It needs to set the stage, send in aid etc. and ramp up building its own local assets and contacts. And even in a year, if it sends engineers etc., there will still be
some casualties. Either you accept that and commit, or don't and stay home. There's no middle ground. And yes, it's a lot easier to say this theoretically, then to commit some poor worker's life who's got family back home. These are not easy decisions, but they are strategically important for nations.