The root "vir" in appropriate contexts (though clearly not in all, e.g in `virile`) has long been divorced from its original "male" denotation. The best example is probably in the word "virtus" (in English, "virtue") and further derivatives (e.g "virtuoso", an Italian word which has also been adopted in English), where nobody perceives a denotation of "maleness" any more (even though a long time ago the word was coined to refer to "a male's positive traits" such as courage and strength).

I contend that "triumvir" today has no more denotation of maleness than "virtue" does -- e.g, Merriam-Webster defines it as "one of a commission or ruling body of three" (appropriately gender-neutral) and I think they're spot-on about this.

Alex