Do you think a requirement of being atheist means you have to embarrass kids or be racist? Do you think atheists have a moral obligation to do genuine persecution against people for wearing a robe?
Secularism in education doesn’t mean you have to strictly control what clothes kids wear. Just don’t have private religious schools, it’s as easy as that. That’s what socialist governments do when they have a secular state ideology, they ban religious schools, shelters, hospitals, etc and replace them with secular, public ones. They don’t ban religion outright because that’s absurd, it’s a waste of time, and it’s needless cruelty.
Why does it matter if some people are Muslim? Do atheists have a moral obligation to control what Muslims wear or believe? Why?