No problem at all

Your hubby is still considered Canadian resident for tax purpose during his absence as he has strong ties in Canada. The reason is he still has spouse, child, and apartment/house in Canada.

So you don't need to report his leaving date on the tax return. You can claim all the deduction/credit as he were in Canada.

On the other hand, your hubby is supposed to report his income from China in his Canadian tax return. I don't think many Chinese Canadian are doing that since it's very hard for Canadian tax department to find out the real income from China.