I think he was referring to the times when short hair on women (esp young women) was a societal sign of unchaste behavior. For example, when a woman was arrested for prostitution, her hair would be cut off so everyone would know.
Then, some women, esp lesbians starting cutting their hair like men… until today where women can cut their hair however they like, even a military cut like some men (even though that’s still not common), without it meaning anything specific. AKA - short hair on a young women doesn’t automatically mean she’s a lesbian, prostitute, etc. Heck, there are lots of nuns who have short hair today.
But in previous centuries, short hair had a very unchaste meaning in many societies.