its not an arguement it was fact. china did recruit many russia scientist after the fall of soviet, and they are willing to pay top $$$ for them, free housing etc etc. after fall of soviet, during and after the chaos many russia scientist was out of job, and want to move out of the country. most of them still belief communism, so moving to another commy country make sense to them, also china pay them very generouslly, including other benefits free house, med care etc etc. on top of that, its much easier for russian scentist to get into china than US or other western country, since western country were suspicious about soviet scentist, and non of the western country actively recruit soviet scentist, which make china to recrut these scentist even more easier. the result of these scentist help china R&D quite a bit.
china avionic, eletronic, etc technology futher improved after most western coporation move their jobs to china. alot technology/innovation were created during manufacture process, this is true for any manufacture anywhere. on top of that china REQUIRE technology transfer when west coporation try to access chinese market or establish local factories. so company such as GM, GE, Mirosoft, IBM etc etc has local partner, and sold/transfer alot technology to china for the past decade. these coporation have research center in china. alot chinese kids educated in US, master/phd went back to china after graduated.
most technology today are dual purpose, espeically in avionic, electronic, optical, computing etc etc etc. as result of ALL these event help china leapfrog in certain fields. their avionic, electronic etc are near the capabilities of west. the jet engine/diesel turbine still lag behind west, radar is a bit behind.
if you open your PC,smarphone, most likely its made in china. the same electronic/processor/chips can be use for aviation, electronic in a jet/ships/satelite etc etc. so the hardware/technology is there for china to use in certain part of their military equipments, missile guidance, sensor, satelite, FBW etc etc
so the reality is every single event that i mention start from 90's till now contrbute to the overall of chinese technology/R&D etc. the recruit of those russian scentist was merely the 1st step, and every event aftward take a step foward for china, and the government also help it by invest tens billions of dollar in R&D, technology firm.
there alot people belief china copy everything etc. it is true they did siginficant reverse engineeing and study of russia/west stuff. but the result is they learn ALOT from the stuff they bought from russia, and combine with above event i mention, they create their own electronic, avionic, radar etc for their jet or ships. have you notice, they buy less and less stuff from russia since 2005. china only interest in high performance jet engine/diesel turbine for combat ships from west/and few other technology. for china, it will be nice to get some new stuff from russia to see how it work, but unlike in the 90's china has the ability to produce its own stuff that is comparable to russia stuff but behind western made products. china seem interest in s400 though