I can understand where he's coming from, but a law suit is overboard.
Being a minority sex in most fields of work is an uncomfortable situation at best. I've worked with all women and I can tell you it is difficult. I imagine it would be worse for a woman to work in a field with all men though.
With women they gossip more, spread lies, back stab, and I have actually seen them actively try to destroy marriages before.
With guys it's just crude. Burping and farting. Maybe a little machismo, but not too bad.
A 50/50 balance is the best environment to work in.