In Act II of the play, Love! Valour! Compassion!, why does Gregory insist that Bobby leave his home?

After learning about his sister's death, Bobby, in his anguish and emotional confusion, confesses to Gregory the affair he had with Ramon on Memorial Day weekend. Shocked, hurt, and angry, Gregory insists that Bobby leave the house that day and fly down to Texas to be with his family and await the arrival of his sister's body from overseas.