[Disclaimer: what follows is just my personal subjective opinion]
If the person being interviewed is a crypto researcher, this means the purpose of the interview is to have the opinion of an expert in cryptography. As such, learning high-level 'thought provoking' information about cryptography to prepare such an interview kind of misses the point, in my opinion: finding this material and reading it is something anyone with a vague scientific background could do. I do not see the point of interviewing a crypto expert if in the end he just repeats what he learned two days ago on Wikipedia.
Maybe this was a mistake of the IT giant to interview an expert and ask him question far from his field. At the same time, I believe that being an expert in any domain requires a strong knowledge of the surrounding area. Your specialized subfield exists in a broader context, has connections to other areas of cryptography. In fact, over-specialization is a plague of science, with more and more people struggling to solve problem when the solution they are looking for has already been found - under another name, perhaps, and in another but related field. There are dozen of examples of this.
So, my point is the following: if you feel like you need some high-level and generic material about crypto to answer an interviewer who contacted you based on your expertise of the field, I'd suggest refusing the interview. At the same time, I would suggest getting prepared for further interviews of this type the hard way: not through Wikipedia, nor through lists of thought-provoking questions, but through a long and dedicated study of all the fundamental results that shaped cryptography. Reading seminal papers in all major subfields of cryptography, regularly following the news through conferences, perhaps organizing a weekly seminar on breakthrough or seminal results in cryptography in your university. Even a researcher on side-channel analysis should be able to describe the GGM PRF construction. Even an expert on indistinguishability obfuscation should have a pretty good idea of the design choice behind AES, and the existing cryptanalytic techniques. Even an expert about discrete-log type cryptography should be able to describe Regev's lattice-based encryption scheme. I guess you get the point. The bonus is, not only will that allow you/your colleague to be more confident in interviews; it will also have very positive impacts on your research by allowing to envision connections to other area, and will help broaden your interactions with the scientific community.