The person who corrected the original commenter seems to recognized that "he" was being used in a gender-neutral way, even offering the use of "they" in its place, most likely as gender-neutral "he" is offensive to some.
However, english does not concern itself with what is or is not offensive. That is entirely up to the user to decide.
> Grammatically acceptable or not, using "he" as a gender-neutral pronoun here introduced confusion.
That gender-neutral "they" was suggested as a suitable replacement here, I don't think that is the case. The fact that we can find another word that unambiguously removes gender from the subject means that gender is irrelevant to the comment in question entirely, leaving no room for confusion with respect to what the message is about, no matter what pronoun is used.