Why is rudy's behavior so dangerous? why does rudy behave so dangerously? what is the result of rudy's behavior? from "the book thief"

In Marcus Zukak's novel The Book Thief, Rudy Steiner behaves in a dangerous fashion. Rudy openly admires the Olympic athlete Jessie Owens, an African-American, something which goes against the white supremacy of Nazi Germany, where he lives.  He becomes active in the anti-Nazi resistance movement due to his disbelief in the Nazi's racist ideology.  His athletic gifts and frequent winning of foot races attracts the attention of the Nazi leadership, especially given Rudy's outspoken doubt in the Nazi party's belief in white supremacy.  Rudy's activity leads to his eventual death at the hand of the Nazis.