From an average reader (a group the thread seems to think is incapable of understanding disclaimers):
Stephens comments do more to "impugn his reputation" than anything else said thus far: they are antagonizing (by making it seem as if Artur's criticisms were intended to undermine Stephen), unprofessional (using ad-hominem jabs unnecessarily), and convey a lack of confidence about his own well-deserved reputation as an excellent translator.
They also justify a quite authoritarian approach to knowledge production – "i know it, you don't, so don't criticize me as it would take me too long to explain it" -- which is dangerous especially as Stephen does not provide an alternative method of criticism. "HOW" should these "nit-picky" criticisms be presented?
If the solution is the avoidance of "incorrect Japanese," that seems reasonable. But the verbiage used ("hours that I don't have explaining my thought process in minute detail (if they're going to be this consistently nitpicky)") seems to blur the lines between general nit-picky criticism and criticism based on incorrect Japanese.