Could it be possible that a prayer was answered by the student praying the rosary and it was promised that if the prayer was granted, appreciation would be shown by publicly wearing the rosary....I am not saying that happened, but it could also go to the rational for the boy wearing it, thats why I say I cannot make a judgment on the religious aspects of this...
I guess I am thrown somewhat off-track because people like Madonna (not Our Blessed Lady, but --- you know who I'm talking about) who started off 30 years ago wearing a rosary as a necklace with the crucifix dangling over her famous flashing breasts, turning the rosary into a slut fashion statement; and then different color rosaries became identifying regalia for gangbangers whose heartfelt interests include drugs, prostitution, and murder.
Sometimes I suffer a painful mix of anger and depression over the way everything sacred to me gets seized upon and perverted by those who sling them around as trifles, or overtly mock our good Lord, our blessed Lady, and all things holy. The tears overflow my eyes.