This claim is quite widely believed by (at least part of) the Chinese military enthuiast community, and has been extensively used as material to attack the 601th institution, so... okay and thanks for clearing their name I guess? Also I really don't see why you're so adament that 601 has absolutely nothing to do with the design of J-20Are you blind?
I specifically said:" Not saying that design can't be changed".
I was disgusted especially because of the claim that 601 worked on the tail of J-20. My ass.
So much for your enlightening!
btw I missed the "Not saying that design can't be changed" part so sorry about that