Nobody said anyone was horrible. It's just that if a group is very dominantly male or female, you feel a bit like an outcast when you are the other sex joining in. Even if they are super welcoming, it's still feels a bit weird.
Also, each sex tends to have a bit of a difference preference on how a meeting-space should be. For example: Most of my male friends tend to hang out in garages/sheds some of the time. Never seen a woman choosing a those locations.
My experience is only that that people are individuals, and whether it's pleasant or educational to have them around or not doesn't have anything to do with gender.
I dunno, maybe ask the woman you quoted:
"While the local men's shed welcomes women, Ms Reardon said there were many women who wanted their own space.
"People like me that would feel intimidated going into what would traditionally be a man's space … want to learn with other women," she said."
The women themselves don't want to be around men because men are so horrible apparently.