The blame ultimately falls on his friend, who trusted them and deposited the funds there. All CEX platforms, without exception, are not considered wallets for storing funds, and anyone who wants to use them should review their ToS carefully to avoid regretting it later.
Many warnings about risk of fund deposit to centralized exchanges and worse store on centralized exchanges a long time. Firstly your first mistake is sending fund to centralized exchange and they can seize your fund immediately. The second mistake is storing your fund in CEX account a long time, and ignore risk of exchange hack, scam exit, bankruptcy and orher things that cause death of an exchange.
https://www.cryptowisser.com/exchange-graveyard/