You have to remember that a minority group will often attempt to reclaim a derogatory term as their own to take the bite out of it. A great example is the term "Yankee" back during the American revolution, but I am sure you can think of a more recent term this has happened to.
Where I come from (central US), "chick" is similar to "dork" in that it can, but doesn't necessarily, have derogatory connotations. It depends a lot on context. It's perfectly acceptable (though slightly cheeky) to call oneself a dork in public, but you typically wouldn't call someone else a dork unless you were already on very familiar terms with that person. And you would only do it in familiar circumstances. Doing it with someone you don't know very well, or doing it in public, would be considered offensive. Doubly so if you don't know them and it's in public.
Chick operates the same way, only it's got even more cultural baggage because it features in a lot of memes that are associated with sexism (e.g., the phrase "cruising for chicks").
So I wouldn't even dream of presuming that it's OK for me to call someone else a chick in public, even if I knew them to be a founding member of Chicks who Code.
I realize that the original poster was probably just trying to be cute. But, as John Scalzi famously observed, "The failure mode of 'clever' is 'asshole'."