Well in his defense we did see that picture of the Type 003 (?) carrier model at some Chinese museum with naval J-20s and drones last year.
But I agree with you that the FC-31 as a platform makes more sense because you can put more aircraft on deck. The J-20 is just too large of an aircraft.
The J20 is about same weight as the F14, and has similar dimensions too. J15 is about same size as well.
Only thing really holding it back is it’s status as an air superiority “duelist”, but the function of bomb truck could be filled by J15 and stealth drones later.