I'm the charge nurse of my unit on days. When the last charge nurse vacated it, I was the most qualified...end of discussion.
The highest ranking chief of my facility is female, however, all other other VP positions under her (which over the last decade she's hired) are held by males, including the VP of patient care that covers nursing. So you might be onto something.
I have heard stories of favoritism for male nurses, but honestly I haven't seen it, as most of the males in charge have earned it. All the managers, but for one, and all the directors where I work are females (it's their bosses who are all male, like I stated above). So men haven't made many strides there.
But male favoritism in leadership positions obviously isn't unheard of.