He said, ironically speaking with authority on something he had no idea about..

"classification by compilation" is literally part of the Security Classification Guide (SCG) and given as mandatory training to everyone with a clearance at least once a year. Individually unclassified pieces of information can absolutely become sensitive or even classified when aggregated. Read the SCG people, this is not rocket science.

(I am not saying that applies here to this data. Merely stating that none of you have any idea what you are talking about.)