> It's merely an abbreviated use of "mankind," which is an abbreviated use of "humankind."
"Humankind", "Mankind" (and "man" when used in a sense that is semantically-equivalent to the other two) are mass nouns that do not take articles ("the" or "a"). In the case of "humankind" or "mankind", using an article is just plain incorrect (consider, "one giant leap for the mankind" vs. "one giant leap for mankind"), whereas for "man" the use of an article can distinguish between the sense of "an individual adult male human" and "humankind" (consider "the story of man" vs. "the story of a man".)
So, no, in "for the modern man", "man" doesn't work as a shortened form of "mankind".
> The use of man in this context is androgynous.
No, its not, even if it was intended that way.
> It's merely an abbreviated use of "mankind," which is an abbreviated use of "humankind."
"Humankind", "Mankind" (and "man" when used in a sense that is semantically-equivalent to the other two) are mass nouns that do not take articles ("the" or "a"). In the case of "humankind" or "mankind", using an article is just plain incorrect (consider, "one giant leap for the mankind" vs. "one giant leap for mankind"), whereas for "man" the use of an article can distinguish between the sense of "an individual adult male human" and "humankind" (consider "the story of man" vs. "the story of a man".)
So, no, in "for the modern man", "man" doesn't work as a shortened form of "mankind".