I am not sure why you want nomadic Arabs to wear hats and why would you want Arabs in shul during davening.
I think what he is talking about is if an unmarried Jewish boy must wear a hat during morning prayers. While ideally you should wear a hat on top of your skullcap outside of yeshivas most shuls don’t. Many shuls require the leader of prayers to wear a hat and jacket but if the Rabbi isn’t there you can get away without it if you have the tallis on top of your head.
Females who are not married do not require a head covering to pray.