You're right; however, there is a major distinction between OJ and Rittenhouse that was mentioned earlier: OJ was already a well known and established public figure, whereas Rittenhouse was not. What this means is that the opinion pieces and libelous statements that MADE him a public figure might still well be actionable since the standards for libel and slander are lower when the figure in question is not a "public figure" and since it was misreporting and opinionating about the incident that made him a public figure, he might have a stronger case.
Possible. The one issue I can see with that is the claim it was the libelous comments specifically that made him a public figure, vs the incident in general making him a public figure and the libelous comments were merely part of the overall media coverage.