So even with your good parenting, you can't trust your child to stay put right outside the restroom, while you take care of business? If good parenting is enough to keep them in place inside the restroom, it should be enough to keep them in place 15 feet away outside of the restroom.
Even if you bring them inside with you, how would you stop someone from trying to take them while you are inside of a stall, with the door locked, and your pants down around your ankles? If you can't leave your kids outside because you are afraid of what might happen, the only real way of keeping them safe is to take them in the stall with you. Not standing on the other side of a locked door. If anyone's modesty should be forfeit in order to keep a child safe, it should be the parent's. Not everyone else's.
I also think you must hold men in pretty low esteem if you think they would all just stand by while someone took your children, or tried to do something to them while inside the mens room.