It's like a man whose sense of his own masculinity is so fragile, he can't bear anything that even hints he might be gay. Or something like that. I think you're spot on with anti-knitting being sexist. And for the woman who got an F for suggesting knitting is an art, that's pretty much true of all so-called crafts. Knitting, needlepoint, quilting, sewing, etc.
Art is what people do that is anything more than just ulititarian.
Putting two pieces of material together with batting becomes art when the fabrics are selected for style, color whatever. But it's like literature. I'm not, but I don't think less of people who like to cook, knit, etc. I sew, anyway. And if I happen to prefer my power saw to a crochet hook, I don't think all women have to be that way or be labeled as wimps.