As I understand it, he's suggesting that HTTP should incorporate something equivalent to STARTTLS as seen in some form in IMAP, POP3, FTP, LDAP, Postgres, and probably several others I'm forgrttingg
Ideally, we should be using DANE or some other kind of signed broadcasted info. Telling the user what happened is just a very good workaround (that will stay useful even if we change to DANE).