The alt-right a loose collection (with overlaps) of January 6th supporters, anti-vaccination activists, people who believe the election was stolen, white supremacists, and so forth.

Ben Shapiro is pro-vax, does not believe the election was stolen, and has had the FBI arrest alt-right people who made death threats against him multiple times over the years. "Poster child of the movement?" Unless you consider alt-right to be completely the same as far-right, that was never the case. No movement makes death threats against their poster child.