I find myself agreeing with Brennan here, the Nazi's powerful propaganda system was indeed one of the enablers of the Holocaust. I mean Hitler killed his opponents who openly criticized him and threatened his grip on the nation, that right there is extreme censorship and once that's in place anything can happen.
The majority of Germans never would support mass extermination of Jews, that's a matter of record, so given that fact we cannot easily dismiss censorship as a key enabler of it.
Most Americans I meet know jack shit about the history of the Third Reich or history in general, even the USA's own history.