My impression was that it was the private bus companies that enforced these policies, and the government simply did not stop them. Hence the Montgomery bus boycott, as opposed to the Montgomery petitioning of the Alabama government to change the law. (I also wonder: were city buses still owned by private companies in the Northeast in the 1950s?)
As if racism was just some disembodied element like hot weather or malaria that the South had to suffer from. Try changing that to the active voice: “because white Southerners were racist” (and the past tense is mighty generous: if you are going to pretend most of them are magically no longer racist because the Yankee-controlled federal government forced them not to be, I’m going to have to side-eye that bigtime, especially given how much that would tend to implicitly contradict a lot of the rest of your ideological positioning).
ETA: Please stop using the “Democrat Party” slur, unless you can show that this usage was prevalent when the Democratic Party dominated the “solid South”.