What's Nudity?

Is it fair that Facebook can ban political statements that include female breasts?
Here's a short graphic history of nudity, and one woman's view that the ban on female nipples is unfair.

Facebook's Community Standards page makes an exception for "depicting acts of protest," but not for education. It barred the last link below about "toplessness" even though I hit the "remove preview" button...

"1936: Male bare-chestedness is made legal in the United States."
Though I couldn't find when it was made illegal...
From: Wikipedia: Timeline of non-sexual social nudity

"In a Dear Abby letter from 1956, a woman asked if it was okay that her son and daughter attended dinner nude. The response from Abby was: Of course it's okay, being nude is a very healthy way of living, and many families all over the United States allow their sons and daughters to attend picnics and dinners nude."
I recommend reading the whole article (with photos), on Quora, saying nudity was common in the 1930's-1950's.

"Male nudity in the US and other Western countries was not a taboo for much of the 20th century. Social attitudes maintained that it was healthy and normal for men and boys to be nude around each other and schools, gymnasia, and other such organizations typically required nude male swimming... Movies, advertisements, and other media frequently showed nude male bathing or swimming. There was less tolerance for female nudity ... Nonetheless, some schools did allow girls to swim nude if they wished. To cite one example, Detroit public schools began allowing nude female swimming in 1947, but ended it after a few weeks following protests from parents. Other schools continued allowing it, but it was never a universally accepted practice like nude male swimming. When Title IX implemented equality in education in 1972, pools became co-ed, ending the era of nude male swimming. A generation later many deny that the practice ever existed."
From Wikipedia: History_of_nudity:

"A wide-ranging review of 190 different societies during 1951 found that few insisted that women conceal their breasts. In Europe, topless swimming and sunbathing on public beaches has become socially acceptable. In 1994-95, Australian researchers asked 118 college-age students to rate the behavior of women who go topless on an 8-point scale, ranging from "Women should have the same right to topless as men" to "Topless women are exhibitionists". They found that 88% of Australian university students of either gender considered it acceptable for women to go topless on public beaches, although they felt that women exposing their breasts in other contexts, such as public parks, was inappropriate. They did not find a correlation between exposed breasts and sexuality in social situations."
From: Wikipedia: Toplessness

In most states, it's legal for women to be topless- but not all. GoTopless.org has a map. Note that in some places it's legal for women to be topless but not to post a sign or photo showing it.

Here's an article from 2016 with more details about the states and their various laws.

And Wikipedia: On indecent exposure.