Probably classified questions. Those could be done in any secure facility but then it is possible that Brennan was given a chance to pull up old notes on CIA systems. Or ‘twas like you say and just a friendly interview.
Probably like Hillary’s fake interview. Almost certainly current CIA employees where there to “help” him answer questions.
Probably like Hillarys fake interview.
Did they serve tea and crumpets and have Susan Rice there too?