Imagine this headline was "Hiring boys is difficult (because very few work in the space)" I would think you'd be having a hard time because kids ("boys"/"girls") aren't usually into coding coding in Kindergarten. Look at your words - they convey a lot.
Ask yourself if you would ever work for a company that was looking for "boys" (not Men). It seems quite disrespectful to women and I'm just a "boy".
I agree that infantilizing language shouldn't be used, but the company wasn't looking for "Girls" and filtering out "Men", it was looking for "Girls" and filtering out "Guys". So in context, it seems more casual than infantile. The point which really drives this home is actually a comment on the article itself, which slams the author (like you and others here have) for using the dreaded term "girls", and then turns right around and says "Attend Women 2.0 events and check out Girls Who Code", with no hint of ironic awareness.
Words convey a lot, but so does context and tone. Unless you can point to something specific in the article which infantilizes women and indicates that "girls" is being used in the child sense and not the casual sense, I think your ire could be better pointed somewhere else.