This is a interesting question, which gets to something much deeper and more profound. There are two places in the memoir where Elie Wiesel explicitly mentions Beethoven. In the first instance, he say that Jews were not allowed to play Beethoven, because Jews were not permitted to play German composers. This is to show, in part, how racist the Germans were. The German hatred was completely irrational and it extended to music. He writes:
We struck up conversations with our neighbors, the musicians. Almost all of them were Jews. Juliek, a Pole with eyeglasses and a cynical smile in a pale face. Louis, a native of Holland, a well- known violinist. He complained that they would not let him play Beethoven; Jews were not allowed to play German music. Hans, the young man from Berlin, was full of wit. The foreman was a Pole: Franek, a former student in Warsaw.
The second time he mentions Beethoven is when Juliek is playing a fragment of a Beethoven concerto. This is a powerful scene in the book. Wiesel says that Juliek played his final concert for an audience of dying and dead men.
In conclusion, the pathological hatred for the Jews described in the memoir is extreme. This Beethoven bit is only the tip of the iceberg.