I think what's more accurate is that MN is now different to it's initial state. As mentioned, I used it a lot some 10, maybe 15 yes ago. And it was certainly a female forum, whether intended or not. I know there's a male poster that said earlier "wrong, I was on it" and fair play, he may have been. I used it loads and didn't encounter anyone who said they were a man, categorically, not once. Whereas now, many posters are male and present themselves as such.
I rejoined, probably a couple of years ago, and it's a really different mix of posters. I don't think that's anything to get your knickers in a twist over, but it's definitely not the "just female" forum it was way back then.
Because that's how I first found it, and heavily used it, this time round, when someone says they are a man, I do still have a momentary "oh!" But that's about the extent of it. It's not an "oh, what are you doing here? Get off"
I think it felt like a safer space back then, to me anyway, but not because it was more female, just because inherently then internet has grown into somewhere less safe in almost every respect. There were just as many bunfights. Less journalists hovering over everything and level of trolling though.
Ten years ago, to me, MN was for women, predominantly, mainly but not exclusively, mums. Today it's a free for all, but I still find it my go to for help (on which paint someone would recommend, which trainers are good value, does anyone know a good restaurant in xyz) for entertainment (love the Christmas boards) and a place to have some really good discussions.