why the author mention "gestalt or est or the 1970s Californian human-potential seminars"?

the preceding sentence is "you don't summon the cynical elite of the West Coast press corps, with their notebooks open and their cassette tapes rolling, to participate in some kind of group therapy session"

There's a lot of cultural stereotyping going on here, contrasting the all-business, tightly-controlled, never emotional, always rational businessman (in the stereotype), versus the give-vent-to-all-your emotions, say whatever is on your mind, go for an emotional catharsis, share your feelings, of the hippie and post-hippie worldview, as characterized by California new-age self-improvement fads of the 1970s and 1980s in the stereotype (California is often seen as the center for new and outre lifestyles and movements). The businessman uncharacteristically goes hippie on everybody is sort of the viewpoint of the writer. Encounter groups, primal scream, gestalt, and est were the names of various forms of somewhat faddish self-inprovement programs in the 70s.