In military/spy discussions, “open source” means “doesn’t require a spy to collect” ( https://en.wikipedia.org/wiki/Open-source_intelligence ).

Open Source is used here in the same sense as in "OSINT," Open Source intelligence, which is gathering publicly available data to infer information that your targets likely wouldn't volunteer directly.

I assume you are referring to this bit. > The researchers discovered that you can find out a lot from open source data, including Facebook profiles and people-search websites

It had me wondering too.