MITM isn’t the issue… it’s the inability to resolve without the NNS note. If you want to connect to a new relay and you only have the NNS name of the new relay, you literally can’t connect if your current set of relays don’t know its IP. You literally have to ask your relays for permission to join new relays… because if they withhold the IP, you can’t resolve the NNS and you’re fucked.