Well he's sort of right from his own perspective. The first HQ-9 was heavily influenced by the S-300PMU and most of it was a direct copy. China eventually changed the radars units a little and
@Tam should be able to explain more of the details since he's familiar. Since then, the HQ-9 series have evolved to become something quite different from where the S-300 evolved, S-400.
Without PLA buying and reverse engineering S-300, the first HQ-9 (or whatever PLA's long range SAM would be called) would likely be something very different. Even the missiles were nearly identical when the "family line" branched off. Not sure why this is important though.