I think the contrast is supposed to be the difference between always monitoring people who post about protesting FOR X and/or protesting AGAINST X versus search

I think the contrast is supposed to be the difference between always monitoring people who post about protesting FOR X and/or protesting AGAINST X versus searching for posts of people who were near some incident related to some protesting or some crime. It is similar to the geo-fence search warrants that were recently discussed here. tl;dr: I see it as the difference between using search tools to monitor for potential suspects vs search tools to implicate already identified suspects.