What it means is that they require suitable underwear to accommodate their genitals; in a similar way to girls wearing a bra.
So you would tell boys what type of underwear to wear? Even though tight fitting pants aren't healthy and many find them uncomfortable?
And girls are made to wear bras are they?
Plenty of women on MN say they no longer wear bras because they aren't comfortable.
But hey. Let's tell boys what underwear they are allowed to wear simply because you insist that if boys are given a uniform choice it has to be skirts or trousers, the same as girls, even though girls and boys are different and have different bodies.
So you'll accept boys being told what to wear, even down to underwear choice when that would be outrageous if anyone told girls what style knickers to wear, right?
Because God forbid, we should try to treat boys equally with regards to clothing.