There are likely lots of historical, social, and cultural reasons why knitting happens to be more popular among women than men -- reasons that might go back to our hunter-gatherer days, when the stronger, more physically capable men were the ones going out to hunt while women stayed home and took care of, among other things, the creation of clothing.
I wouldn't describe knitting as a flow state in the same way. I frequently listen to podcasts, watch movies, listen to music, etc, when I knit. Knitting is... I dunno... rhythmic?
Now granted that depends. If I'm working cables or some sort of motif or whatever, it can require a bit of focus. But it's definitely not the same as coding. And if the fabric is simple stockinette or something, I don't even need to look at my hands.
It's also not at all solitary unless you want it to be. Knitting circles are a very common thing and I personally love hanging out with my other friends while we each work on projects.
In short: my guess is your confusion is mainly borne of a misunderstanding of the hobby.
My suggestion? Give it a shot! YouTube has made it easier than ever to learn, and a pair of sticks and a ball of yarn will cost you less than ten bucks. You never know, you might love it!
Creative hobbies do tend to be a bit male-coded or female-coded for various reasons. For some hobbies I suspect that the very single-sexiness of the hobby is part of the appeal — women join knitting circles as an excuse to hang out with other women, men go golfing as a way to hang out with other men.