My sons reception class teacher is a man and I love it. Some of the kids (thankfully not mine) need a solid, friendly, supportive and active male role model and if it can be their teacher then fantastic. He is 10 times the teacher he replaced as well.

Also my brother in law is a nursery worker and I honestly couldn’t place someone better in his role. He was made for it. The persons gender is irrelevant, it’s all about their personality. My sons teachers prior to this current chap were both female and both absolutely dire. Nothing to do with their gender tho, just their personalities and their approach to life/kids. I’d take this chap over 100 ‘can’t be arsed’ female teachers any day of any term. But I reckon your MIL probably wouldn’t.

Your MIL is being ridiculous in my opinion. It’s 2019 not 1754.