It just struck me the Chinese must be on the horns of a dilemma. Pass on the best weapons in their arsenal to India be it the HQ-19 or the J-35 & they risk a few things namely -The exact specs of the Pakistani HQ-19 are yet to be revealed. You can expect a lot of fud around it in the days to come.
If the system can intercept IRBM-class targets, I'd imagine any sale would be restricted under MTCR. Maybe this is an export version with downgraded capabilities?
1.) risk being exposed once again for supplying junk but get an insight into how India'd prosecute its wars against China
2.) assuming they do get the better of India , that'd prompt India to go back to the drawing board & modenize aggressively which you don't want if you intend to go up against India later this decade
3.) then there's this obvious risk of avoiding the prying eyes of the US for let's face it this is Paxtan we're talking about where everything is for sale & everyone has a price.