You would have warned them about the possible blackmailing a centralized exchange is about to do, that's what he's telling you. The centralized exchange wants all of your info, so simple. You can't choose to mix, because that's against their rules.

Show them what's a P2P exchange, they're gonna love the idea if they're interested in this field. Those who don't care about handing out their custody will neither care about their privacy, the censoring, the blackmailing, the dictating attitude, the arbitrary fee rate etc.