Well he has a point. Russia has been working on a 4th Generation fighter for the past 30 years. 16 years looks pretty good for Su57, till you remember that its filling a role initially intended for Mig 1.44. There is still no commitment to buy large numbers of Su57, even after 8 years of testing.
If Russia buys in small, affordable batches, they are going to be suffering obsolescence problems before you even complete the buy. That and the cost is likely going to spiral, as they keep production lines open that aren't fully being utilized.
Its no criticism of the aircraft to suggest the procurement of it clearly has issues. It seems to me that the Ruaf has to make a decision whether it wants large numbers of affordable aircraft, or small number's of state of the art aircraft. Pretty clearly they seem unable to make their mind up because they are seemingly trying to go down both tracks.
I hope it makes it, I really do, for the record.