China could easily just declare that they'd be willing to support Niger against the ecowas terrorists and then those dogs wouldn't dare to invade the country. I understand how China delivering arms to Russian forces in Ukraine might be too risky (although even then I seriously doubt the West would be stubborn enough to crash the entire world economy and cripple themselves just for their fascist puppet state) but what does China have to loose in Africa?
Others have mentioned China's non-interference policy, I'd like to add that I think the only way for China to get more involved is through the UN, that means the Security Council or Peacekeeping or some other UN organization.