I don’t believe in banning artists at all. Wagner was a genuis, no denying and I love his music - although some of it does drone on a bit. Fonda was a fair actress who gave one or two decent performances in film and coasted for the next 30 years. The New York Times actually has a HIT piece on her today, btw. Check it out, you’ll enjoy it.
Please read some of the writings of Wagner on the Jews. They are stomach-churning. As this article points out, after Wagner’s death, his awful wife Cosima attempted to bail Hitler out of jail (forgot about that one!) and had her grand kiddies dandle on his knee. The whole creepy family were Nazis!
It’s the ultimate paradox, isn’t it?
I believe they may be confusing Cosima with her DiL Winifred. Cosima was a very old and infirm lady by the time Hitler rose to prominence. I'm not sure she could really be faulted (much) for supporting him anyway, since she died in 1930, well before he took power. It's not like she or anyone else could see into the future, any more than we can.
Winifred, OTOH -- who was English, not German -- was a die-hard, unrepentant Nazi, even after the war. People even speculated that she was one of Hitler's girlfriends.