I realize I'm about a month behind with this (it happens sometimes), but I just spent some time exploring the ALA's site for information on banned & challenged books (linked here) and I recommend you do the same. The ALA writes we need to be aware of all attempts to censor literature, and that "Censorship can be subtle, almost imperceptible, as well as blatant and overt, but, nonetheless, harmful." I was also happy to see a quote from John Stuart Mill's On Liberty - sort of a nice little callback to 502! There's also a very informative timeline to celebrate the 30th anniversary of Banned Books Week (found here), highlighting significant challenged and banned books from 1982-on.
Overall, I highly enjoyed reading through the reasons people and institutions come up with for challenging classic books - most of which are, for lack of a better word, completely insane (in this author's opinion). I was pleased to learn that quite a few of the most highly challenged classics were required readings for me in both junior high and high school. Looking back on it from this point in my life, I'm thankful that my teachers assigned these novels despite the risk of complaints from parents and other school higher-ups.