I believe you're misreading Zinn. I have the 2015 Routledge edition at hand, and nowhere in that edition does Zinn characterize the Iroquois using that language.

The closest reference I've found to what you mention is on page 20, where Zinn discusses the Iroquois' matrilineal, communalist lifestyle, that was organized from the bottom up, then sets it against the radical Pilgrims that settled New England. "All of this was in sharp contrast to European values as brought over by the first colonists, a society of rich and poor, controlled by priests, by governors, by male heads of families," Zinn writes.

Your characterization of Zinn's writing is inaccurate and anachronistic. Zinn is merely comparing Iroquois society to that of the first English settlers in New England, who were conservative radicals governed by a governmental and religious structure wholly different from Native society. Iroquois society was not egalitarian, feminist or progressive by modern standards, but it was certainly more accommodating to women, to non-binary genders, and to individual rights and privileges than were the first colonies of New England.

Iroquois society was no paradise. Slaveholding was an integral part of the confederacy, and its aggressive foreign policy meant it conducted frequent wars of conquest and intimidation against other Native nations, using its power to acquire significant amounts of firearms from European traders, then leveraging that firepower superiority in combat.

If you're interested in learning more about the confederacy, I'd suggest Dean Snow's The Iroquois, which was designed as a readable introduction to the confederacy's society.

I'm hesitant to ascribe too much of the modern concepts of 'feminist' and 'progressive' to centuries-old Iroquois. Also my knowledge is pretty limited to 18th and early 19th century Iroquois, but for that time period, the claim of 'egalitarian/feminist/progressive' is broadly true from the things I've read.

Iroquois traditionally did not have permanent, private ownership of land. Land belonged to the nation, but you had some rights to it as long as you were using it. As soon as you stopped planting on it and moved away, you no longer had a claim to the land. By extension, the amount of wealth that could be accumulated in Iroquois society was significantly less than in the hierarchical farming societies of Europe.

Iroquois society was matrilineal, meaning that family membership passed through the mother's line. By contrast, European society is patrilineal, meaning family membership passes through the father's line.

In European society, for a man concerned with the inheritance of lands and wealth, it is very important for him to know who his children are. This requires that the rights of women be constrained so that he can be certain that any children his wife bears were fathered by him.

In Iroquois society, a woman's children are a legitimate part of her family no matter who their father is. Sexual relationships were more fluid and often temporary in Iroquois society. A husband would move into the house of his wife's family, not the other way around. If the wife wanted to divorce her husband, she would simply move his belongings out of the house. In such a society, the permanency of the mother's blood family was more important to the lives of her children than the biological father. Children's maternal uncles usually performed the father-figure roles.

So yes, in classic Iroquoian society, women had a lot more freedom than women did in European society at the time. There is even a movie-worthy account of an aging Iroquois woman (of the Oneida nation) named 'Two Kettles Together' fighting from horseback with two pistols on the side of the Americans during the Revolution at the Battle of Oriskany. (Forgotten Allies: The Oneida Indians and the American Revolution by Joseph T. Glatthaar and James Kirby Martin)

Be careful about romanticizing the Iroquois too much with the myth of the 'Noble Savage'. While some aspects of traditional Iroquois culture are appealing to modern readers, there are other parts that would not be. Let's just say that there is a lot of greed and murder. You can read about both the positive and negative in the books below.

Probably the best and most accessible primary source for Iroquois life in the late 18th and early 19th century is Narrative of the Life of Mrs. Mary Jemison by James Seaver. Mary Jemison was the daughter of British immigrants who settled in the American frontier and were then killed in a raid by the Seneca (one of the original 5 nations of the Iroquois confederacy). Mary Jemison's parents and siblings were killed, but she was spared and was adopted by the Seneca at 12 years old. She would live the rest of her life as a Seneca. As an old woman, she narrated the story of her life to James Seaver, who wrote the book about her life. It is a classic ethnography and window into Iroquois society.

The Death and Rebirth of the Seneca by Anthony Wallace is an excellent, and approachable ethnography of the Seneca in the decades following the American Revolution. If memory serves, it provides a lot of evidence for the egalitarian/feminist/progressive claim.

If you are up for more of a challenge, The League of the Iroquois by Lewis Henry Morgan was a groundbreaking early ethnography of the Iroquois. It's a slog though. I recommend the "ethnographic core" edition edited by Russel Jenkins.

It should be noted that all of the books I've mentioned are primarily about the Seneca, who were the western-most nation of the Iroquois Confederacy. This is partly because they were a large and powerful nation, but also because of geographical happenstance. As the western-most nation, they were the last of the nations to be forced off of their land and onto reservations as the tide of settlers moved west across the continent.

EDIT: Various spelling and grammar errors fixed.

Additional question; if evidence is lacking could it be an example of the 'noble savage' archetype?

Would non-Iroquois examples be welcome? Or were you just interested in that specific example?