When it comes to specific elements of a series' fiction or lore, Game Informer frequently gets things wrong. They've called Deku Babas "Deku Bobbas" and they called a regular Stalfos in Skyward Sword a "Stalfos Knight", you know despite the fact that in every recent Zelda game normal Stalfos act like that. The Ghirahim thing is either a joke or just another issue like that. But given that they cover video games in their entirety, mistakes make sense and are understandable.
Either way, Ghirahim is in no way female. Absolutely impossible. His voice, when heard in his standard Zelda-style grunt sound effects, is
distinctly male. But even aside from that, the only way someone could even remotely suggest Ghirahim is male is if they never really got a close look at him or had no knowledge whatsoever of human anatomy.
Male. Not female. Not to be vulgar, but you can even tell he has a package.