It means that someone has read up on a subject, as well as taken into consideration the professional opinions of others in determining their POV on the subject. But it all depends on what the researcher intends, and/or what he really desires to find out that matters. If I wanted to find out something negative with, say, the COVID – 19 vaccines, I surely could. And I might state to others that I had undertaken “extensive research” in a attempt to fully convince those others of my opinions, right or wrong, biased or not. The two people on Facebook that you mentioned could be terrorists or similar.