So, to answer the question: Do dudes rule the fantasy genre?
Not in mom's house. Not in mine either.
Neither gender rules the genre.
Now, Sci-Fi is a wholly separate issue. Mom and I are not avid readers of the genre as a whole. I prefer creatures and magic over machines and science. I'd say it's a personal thing, but I'm not wholly certain that it is. The male bias in the publishing field is reflecting society's bias (men still dominate the sciences), which (I may be beaten for this) is reflecting the differences in the way women and men perceive and analyze the real world. Gender differences are not justifiable excuses for exclusion in publishing or acceptable explanations for what James's friend is enduring at the hands of her publisher's marketing team.
If I were to organize Mom's library by genre then by author, Sci-Fi books might occupy one shelf. Maybe two. The Sci-Fi books in my mother's library are there because they were written by authors who predominately write fantasy. Of the female fantasy authors who dabbled in Sci-Fi, most of them co-wrote that Sci-Fi novel with a man. I wonder if those books were co-authored because the writers truly wanted to work together or if the publisher inflicted one author upon the other for "credibility."
Dudes rule Sci-Fi, but their domination is threatened by the sub-genre of Steampunk. Women -- readers and writers -- seem to be eagerly embracing that sub-genre. Plenty of men write fictional history about dirigibles and clockwork-machines, but women are decidedly gaining ground.
The guaranteed way to change publishing's Sci-Fi gender bias is for consumers to change what they purchase. If readers buy more Sci-Fi books written by women, then the almighty dollar ensures publishers contract more Sci-Fi books written by women.
There are wonderful women writing excellent Sci-Fi, our own Marcella Burnard among them. Her Enemy books are definitely on my keeper shelf. What about you, dear reader, what Sci-Fi novels written by women would you recommend?