The definition of public figure is nebulous, and sometimes it can even be argued a regular person becomes a ”limited purpose public figure” if they are involved in a public controversy.
Stossel isn’t even an argument because again, he used to host 20/20 on ABC and has been a broadcaster for 30 some odd years. He’s a public figure. But using a real world example, I’m not famous, but by any legal standard, I would be considered a public figure because I have a Wikipedia page, I'm verified on every major social network, I’ve appeared on television, and I’m recognized as a prominent person in the various industries that I have worked in. I know this, not because I’ve ever wanted to sue someone for libel or defamation, but because there have been a few isolated incidents where I received harassment/death threats/rape threats via my work addresses (which obligates me to report them to law enforcement), and the amount of fucks police in the US are willing to give about idle threats to public figures are almost zero. I’m generally OK with this (I have only ever reported threats when I’ve been required to do so my company policy), but it is what it is.
Even taking legal protections out of it and just looking policy enforcement, according to Facebook's terms of service, people can call for my death on their platform, provided they don’t tag me. But if someone says, “Christina Warren should just die already,” that’s completely fine according to Facebook's own terms of service, because they consider me a public figure. Now if someone directly tags me, that may or may not be harassment, but even though Facebook isn’t the same as legal requirements, it shows their own rules are different for public figures.