[rm445]

Why would they address him with a title he didn't possess? And why would that be demeaning?

Academics tend to guard jealously their hard-won academic titles, and also to strive for accuracy in the things they do. An unsolicited 'Dr' might be extended as a courtesy to a graduand, i.e. someone who has already submitted and successfully defended their thesis viva voce. But surely not to someone who is merely 'finishing up' - a process that might never terminate.