So my suggestion is:
1. Ask Border INS for some mercy. That worked for us. He might get a temporary 14 days I-94 to return to US.
2 Ask Chinese embassy for help. I heard that someone run into this kind of trouble before. Actually it seems that he got arrested because he didn't have Mexico visa. Chinese embassy there got him out and he was able to go back to China.
Hope that help. let me know if I can be of more help.
2.