This is IMO the true danger of PC. Anyone with half a brain can avoid a list of 10 slurs and be as bigoted as they want because society is hyperfocused on language policing.
If we paid attention to what people were saying rather than how they said it (i.e. we stopped caring if they use "bad words" and just listened), we would catch more bigotry, not less.
PC also makes people hypersensitive to imagined sleights and hidden messages, it makes it possible as you say for real bigotry be communicated through a culture of code and conduct.
That is true. PC also go beyond the word choice and into the realm of acceptable opinions and arguments, the highest value is no longer to defend others right to speak when disagreeing
