That's the Common mistake  most newbie normally make, i know too well that someone who's deep into cryptocurrency Will never make such mistake, by connecting his wallet to a malicious site as you said, I guess he don't know the risk involve in doing that, he just make those  scammers to gain access to his wallet either. At this point I know most people will blame trust wallet, that trust wallet is never to be trusted.however I hope all his assets is not been stored there?