I think it is great that performing artists, who have a huge pulpit, voice their opinions about pressing world issues. One cannot separate politics from life, or art, for that matter (e.g. Picasso's Guernica), and artists' ability to influence the masses, hopefully in a positive way, can assist with needed changes.
Furtwangler decided to remain in Nazi Germany so the populace would have access to wonderful music such as Beethoven, yet he, unlike Karajan, never joined the party, and consistently refused to go along with the Nazi agenda. He was often critical of the regime, refused to shake Hitler's hand on at least one witnessed occasion, and was earmarked for death by the Gestapo near the end of the war, but he managed to escape to Switzerland.