Normally, especially as a child, if you are flasely blamed for something and you know you haven't done it, in fact you know who the real culprit is, you will give out the wrong doers name, so that people would want stop accusing you that is normal as a kid.
Atharav is a kid right now, yet he stayed quiet for chutki, a girl who he had just bought hope, was she a younger siblings, was she an extremely closed friend. Just a person he met a while ago, someone he just made a friend a day ago, yet he stuck up for her. He stayed quiet even when he was about to be punished for her faults.
Being just a child, he understood his responsibility, he bought the girl home, she did something wrong, but he was the one who bought her so taking up his responsibility he took the blame.