No, Sandmann had no trouble establishing that he was not a public person, because he committed no act or took no action of his own volition that made him a public person.
He just stood there doing nothing and smiling.
It was the libelous reporting that made him famous. The press doesn’t get to make someone famous via fake news and then claim the Sullivan standard exempts them because the person is now a “public figure”.
The same cannot be said for Rittenhouse. He became a public person by publicly shooting 3 assailants, killing two. He made overt public acts that made him famous. He would have been famous irrespective of biased media reporting. So to prevail he has to show the media made false statements with knowledge of or reckless disregard for its falsity.
That’s a really high bar. Oth, SCOTUS has been making noises about the Sullivan standard needing reconsidered and media might settle quickly because they know SCOTUS is fed up with their toxic clickbaity reporting and they don’t want to win in the lower courts based on Sullivan only to lose by being appealed up to SCOTUS.
They know they’re on thin ice because they’ve libeled many Justices over the years and their victims are now the majority.
Clarence Thomas and Brett Kavanaugh are 2 obvious examples.
And in the case of Clarence Thomas, he's stated publicly that Sullivan needs to be revisited.
https://www.mondaq.com/unitedstates/libel-defamation/1090560/supreme-court-justice-clarence-thomas-speaks-up-about-new-york-times-v-sullivan
One good line of attack, IMHO, would be lowering the bar to show "actual malice". After all, why the heck else were Trump, Brett Kavanaugh, and others tormented with such outlandish accusations?
Another possibility would be allowing victims to show a pattern of slander, especially if the pattern continued after the slander had been refuted.