How did Edna Poppy protect Turtle from an assailant in the park? Why was this action especially brave?

Turtle was in the park with Edna Poppy, who was baby-sitting her, when a man attacked Turtle. Because of her blindness, Edna does not know exactly what happened, but she says that she heard struggling and swung her cane in the direction of the noise. Taylor looks at Turtle, whose eyes are as blank as they were when Taylor found her in Oklahoma.