He is not a US citizen for sure.

He said he came to settle dfown in Wuhan so he gave up his American GC.

So he does not need to pay tax to USA on his income earned in China.

If he were a US citizen he defraud Chinese Academy
whose rule says only chinese citizen are eligible.

If he kept his GC in a way, he defruad US department
of homeland security because one can not keep his US GC
is he claim he settle down in a notehr country.