In 1851 and 1852, Mill's Logic and The Principles of Political Economy were reprinted in third editions. By that point, Harriet Taylor and John Stuart Mill had married. In this third edition, exclusively male language was replaced, when possible, with neutral language.
"'Men' was replaced by 'people' or 'mankind' and 'a person' was substituted for 'a man'"(216-217).
A footnote was also added to the Logic:
The pronoun he is the only one available to express all human beings; none having yet bee invented to serve the purpose of designating them generally, without distinguishing them by a characteristic so little worthy of being made the main distinction as that of sex. This is more than a defect in language; tending greatly to prolong the almost universal habit, of thinking and speaking of one-half the human species as the whole.It's too bad this footnote was removed from the 1862 edition, published after Harriet's death.
When I have a student who insists on using exclusive language, I sometimes point to the APA's statement on the matter from the mid-1980's (from before the birthyear of my current students!) but now I have an even earlier philosophical text I can point to.