Ascoyne D'Ascoyne

I watched a dvd of "Carrie" (1951) based on a novel by Theodore Dreiser and starring Laurence Olivier and was surprised by a note to the effect that a scene (which shows a doss-house and its inmates) had been restored as it was never shown at the time of the film's premiere due to the political circumstances of the time.
I know that governments tend to paint a rosy picture of things happening around them but I wonder why the powers-that-were then in America showed such sensitivity over a scene from a story set over forty years previously.