Do you believe that banning books from public schools and public libraries is a form of Political Correctness?
It is a form of parenting, however there are other forms of censure for adults, too. The practical ways to choose censure can never match the ideal ones, so the practical ways censure either too little or too much.
How do you think it relates to Freedom of Speech? Is being "obscene or harmful to minors", by whoever's measure, a sufficient reason to suppress the distribution of books at libraries? After all, adults can still buy them online, so it's not really censorship... or is it?
Considering your comments about capitalist media moguls who abuse their freedom of speech, I have to reinterpret the question. There are very influential media moguls, and they can and do deceive. This wastes our time, resources and harms the union sometimes. True. So then we have to decide what to do about it and how to proceed and how to improve the union (of the people) while not snuffing out the candles of independent thought. Independent thought can be the difference between success and failure, even though it often is full of the dregs of rumors. We should protect the independent whistle blower, the writer, the investigator, the snoop, the muckraker and the creative dissembler etc. These annoying brats often improve the union.
There is a problem, and it is that laws must be handled by geeks parsing formulas and old precedents. This follows from the nature of written laws, whose value is that they are not flippant, not changing to suit whoever is in charge. To keep them requires a system with people professionally dedicated to upholding that kind of parsing, that kind of pedantry and studious involvement. I cannot see a way around this without ruining the whole thing.
The trick is to find a way to set up laws that protect all of the independent thinkers -- but not only laws but principles. Laws to be effective, long term, consistent must embody some principle. Any law made to meet a short sighted goal will easily be changed later, will not be supported in precedents and usually will be found incompatible with the body of other laws. We need principles which the lawyers can interpret methodically, and those principles must protect independent thought and speech but reign in those who abuse free speech. That is difficult to pen.