I can't say, but every time I wind up watching a children's show targeted at girls (usually in a lobby or exercise room), the protagonists are all highly assertive and there's often heavy-handed promotion of the subtext "boys are dumb and useless and it's OK to be a complete asshole to them if it gets you what you want."
Hopefully it's just part of the natural swing towards over-correction and it'll all settle out in another few decades, but a corresponding overcorrection in corporate policy could get ugly. Psychopaths do well enough in the corporate environment as it is.
Imagine if you heard a parent tell their child "don't be an asshole". What gender is the child? I think it's true that women are held to a different standard when it comes to assertiveness, but the existence of a female-specific insult is not evidence of that. There are plenty of male-specific insults of the same nature. Asshole, dick, douche, prick, bastard, etcetera
I do however think that this might lead to girls being discouraged from becoming bosses (a bad thing[1]) while boys being discouraged from becoming assholes (a good thing).
[1] - Or at a minimum, a biased thing.
Let's take a step back and remove gender from the discussion.
My experience working with senior leadership has been to get results you end up stepping on toes. As such you get called all sorts of things.
It's also my experience that the way a person acts towards their boss is different from the way they act with their peers which again is different than the way they act towards their subordinates.
With this in mind are you sure it had anything to do with sexism?
Am I sure? I'm an engineer, so no, I can't be 100% sure.
I think a more enlightening question is:
Are parents/teachers etc being overly unfair towards girls than they would be towards boys for the same bossy behaviour?
I'd argue no. If anything it is the opposite. Only different language is used.
"Rough", "abrasive", "difficult" were the common labels. While there were things she may have done differently, I don't think I'd have seen the same blowback from an identically-acting male leader. I suspect that her experience is common and that if it's gender biased (I think it is), this continual molding could tend to create the outcomes you observe.
Thought experiment: How often do we tell young girls "Don't be so bossy" as compared to how often we say that to young boys?
Or "Imagine that you just heard a mom tell her kid, 'Don't be so bossy!' What gender is the child that she is addressing?"