Son wants to stay home from school next week

My son asked could he stay home from school next Friday. I asked why. He said his health and nutrition class is doing something stupid and only having the boys do it which is "super sexist". I asked what it was and he handed me the booklet they gave them. It's a presentation called mental health in boys and young men. And I checked his Canvas. It's for a grade which his argument is he has an A already so this wouldn't drop it down much. He says he's not depressed so why does he need to go. I told him mental health is more than just depression and if all he has to do is go there and listen then that's a super easy A. He asked why the girls don't have to do it. I said I'm not the teacher. I don't know but no he can't stay home from school that day. So he complained to me to his dad(who hasn't seen him in person for over a year when he lives only 45 minutes away) and his dad is saying I'm being mean🙁