I would be having a chat to the daycare place and ask if he could have quiet time rather than a sleep. Talk to them about the issues you are having due to him being made to have a sleep.
Even at my DS2's creche, they don't force the kids to sleep. They have an area where they can flick through books or play quietly and he is 4yrs olds.
The other issue that doesn't sit well for me, is how do the kids who stay up till 10pm at night get up the next day? My DS1 (7yrs) would be absolutely shattered and not concentrate at school. He would have been the same at 5yrs old.

ETA: sorry, didn't realise you were in China, what do other expats do, can you talk to someone what the protocol is?