Selective sensitivity.
Don't worry, after they are done with "fixing" Jim and Joe they will switch to improving Huck's speech, so that his illiterate English doesn't hurt soft, mushy brains of the readers.
They don't need to bother, of course. Those with mushy brains don't read, so they are safe in front of their 120" TVs. The modern version of 451 °F is much simpler than Bradbury imagined; there is no need to burn books if most people don't want to read.