Even so, when you consider the 'liberal environment' that the site sort of created for itself as a sort of paradigm….something like this is a total inversion of their values. Freedom of sexual and gender expression as well as gender equality is sort of a 'mood' for a large portion of the site. Explicit or not, for many these concepts are intertwined and drawing lines between what is "acceptable" content and what is "not" like back in 1920 is not in line with any progressive or modern thinking.
It also draws lines through communities that are brought together by their sexualities and sexual orientation. Since rules like this are unpredictable and often gender biased as well, even sfw that might border on the 'mildly inappropriate' or 'suggestive' may also be under attack depending on who gets to make the decisions now.