I work at a retail grocery store very similar.We have very strict guidelines to adher by. We have to see them conceal the actual merchandise and then leave the store with the merchandise, all wile constantly observing "shoplifter" to make sure they did not change their minds and put it back. I wouldn't stop until you speak with someone higher up than the store manager. Your son deserves an apology from the D.M and the store manager. A face to face apology.