Visa-free & connection flights

My boyfriend is transiting China from Amsterdam to Thailand, stopping in Guangzhou for 2 days, which I’m assuming is fine. However, on returning from Thailand to Guangzhou (staying in Guangzhou for just over 24 hours until his next flight), his onward flight towards Amsterdam has a connection in Chengdu but it’s only 3 hours layover so he won’t be leaving the airport. Will he still be eligible for the visa free transit or will this route cause problems? Any help would be appreciated!