Actually, "man" in this sense ("all humans") is descended from mann, an old english word that didn't specifically indicate male. It evolved to refer to males specifically later, although retaining its old inclusive meaning.
Also interestingly, the "man" in human is not related etymologically to man by itself.
So the author is actually correct, although the usage is a little archaic.
This usage persists in Swedish where “man” means both the human male and a generic subject for a passive tense, similar to how “one” or “you” works in English.
To me “Man” has more of a “each and every” connotation. Compare
“Man must achieve this.”
“Humanity must achieve this.”
The latter is more of a collective emergent thing. And in some cases that leaves you with a diffusion of responsibility kind of passive feeling, while the former is a call to action.
It's more than just your ear. The way we use language to describe individuals versus groups highlights a divide between personal responsibilities and collective rights. All too often individuals use the group as a means to avoid personal responsibility.
You can if you want, but that ignores how one of the accepted definitions of "man" is humanity. If you're just swapping words without understanding their deeper implications, you might miss the point. It's not about the gendered language; it's about the collective achievements and struggles of all people.
So, are we really focusing on inclusion, or are we just playing word games?
In the original text it is "der Mensch" which translates to "man". It could also be translated to humans but it wouldnt be too accurate of a translation. It also doesnt help that the original is a text from 1967:
https://www.hollein.com/ger/Schriften/Texte/Alles-ist-Archit...
I agree, though the historic roots make "man" (for humanity) and "man" (male person) simply homonyms. They "sound" different in my head, the same way "homo" (Latin for male person) and "homo" (Greek for "same") feel very different to me.
In this case though it's likely simply an artifact of translation from the German word Mann.
It's language specific, I believe. I know in our African language we use Humans (niit) or Children of Adam (domu Adama) when referring humans and humanity.
Also interestingly, the "man" in human is not related etymologically to man by itself.
So the author is actually correct, although the usage is a little archaic.