Linkedin want their data to be scraped by bots so they have to keep it public, otherwise you wouldn't find peoples profile from Google. They just don't want bots from from their competitors like hiQ to scrape it.
To me, this is crucial. If it's public and available for google, it's public and available for everyone. If you want content to be private, then make it private and accept that you won't get search engine traffic. Otherwise, don't be surprised when your publicly accessible content is accessed by gasp the public.