Conservative talk radio host Dennis Prager received a standing ovation from a near-capacity crowd the moment he walked on the stage Wednesday evening to conduct the Santa Monica Symphony Orchestra at Walt Disney Concert Hall. The audience was not only applauding the music, but the principle of freedom of expression, after several left-wing members of the orchestra had attempted to organize a boycott of the event by the musicians and by the public. A letter circulated by the boycotters exhorted: “Please urge your friends to not attend this concert, which helps normalize bigotry in our community.” One boycotter, violinist and...