Even though Political Correctness enforces rigid dogma on Racial matters --- "race is just a social construct", "there are no significant racial differences", etc --- , in truth many individuals in the academia & think-tanks are well-aware that there is a genetic basis to race and racial differences. And these people freely discuss this matter among themselves. So, their main concern is not the discussion of race and racial differences but the 'danger' of this knowledge leaking out to the masses. To these elitists, many of whom are Jewish or white collaborators(cucks or shabbos goyim), the rise of mass consciousness on the Reality of Race is a threat to their own power and privilege since the entire edifice of Political Correctness is built on 'White Guilt' of 'racism' that supposedly constructed wholly artificial racial hierarchies when, all things being equal, every race is capable of achieving as much as any other. Thus, Political Correctness blames 'white racism' for all the social inequalities and problems in the West. This is useful for the Jewish elites because their elite-minority-power rests on suppressing white pride, power, and unity. And nothing has been as effective as 'white guilt', especially since Western Morality is founded on Christian Culture of Conscience.
But in fact, many Jewish elites know that race is real among themselves. They know that blacks tend to make a mess of things because blacks are more aggressive and less intelligent. Also, genetics made blacks more muscular and stronger, which accounts for interracial violence being overwhelmingly black on non-black. Jews and white shabbos goyim know this in their inner circles. But if such knowledge were to become widely disseminated among the white masses, the cult of 'white guilt' would dissipate. White people would realize that it's not their fault that other races have the problem that they do. Thus freed of 'white guilt', white people will think, organize, and operate on basis of white pride, power, and unity. This will threaten Jewish elite-minority-power-and-privilege, especially since Jews have been so hostile toward whites. And since white shabbos goyim(cuck collaborators) depend on Jewish largess, threat to Jewish power is threat to their power(just like threat to Nazi power in France also threatened French collaborators in Vichy). Is it any wonder that not only Jews but Conservatism Inc. is freaked out about the Alt Right that is willing to directly address the issues of race and the Jewish Question?
This is why the Jews want to keep the Realities of Race a SECRET KNOWLEDGE that can only be discussed among the Jewish elitists and their closest allies. As for the white masses, they must be kept in the dark and fed a steady diet of 'race is just a social construct' and 'white guilt'. Some Jewish academics have said that EVEN IF there is scientific truth about racial differences, it must be censored & suppressed for the Social Good. Of course, what these Jews really want is to protect their own power and privilege that is premised on Everlasting 'White Guilt' that paralyzes White Pride & Power.
But such attitude is nothing new in history. The Hindu Brahmins also had their secret knowledge. Their sacred texts could only be read by them for certain peoples. If someone of the wrong caste heard even a bit of this knowledge, the punishment was molten lead poured down their ears.
And in totalitarian-communist nations, the knowledge of the outside world, especially of the capitalist West, was restricted to the elites. The communist elites knew that life was more bountiful in the capitalist West. They themselves enjoyed the goods and entertainment of the the Enemy. But they kept this knowledge within the inner circle while feeding the Official Dogma to the masses since their power and privilege were premised on the 'scientific-materialism' of Marxist-Leninist Doctrine. If the masses were to know the difference between the Capitalist West and Communist East, they could rise up to overthrow the power of communist elites(like what happened in Romania).
So, the communist elites kept the facts about the capitalist West a Secret Knowledge. They themselves wanted to access and enjoy Western luxuries, but they had to censor the truth from the masses who, if enlightened, might demand end to communist rule in favor of market economy.
Jewish elites, Brahmins, and Communist rulers, as keepers of the Secret Knowledge, all invoked the INTERESTS OF THE PEOPLE or NEEDS OF A SACRED ORDER, but their main concern was preserving their own power and privilege. If the masses were to know, they might tell the rulers to go. What the rulers decried as corrupting of the masses was really disruptive to their own power.
And this is why Political Correctness is used to keep certain facts and ideas taboo for everyone but for the elites who believe they and only they should be guardians of the Secret Knowledge.
Insider Trading may be illegal on Wall Street(even though the real insiders do it all the time by 'other means'), but Insider-trading-of-secret-knowledge is the norm in elite circles.
When the Jewish elites attacked Charles Murray, it wasn't primarily because of his views on race and racial differences. If anything, such views had long been aired in elite circles. The problem was he wrote a book for the public, thus playing a Promethean role. Gods didn't punish Prometheus for having the knowledge of fire. They punished him because he took the knowledge of fire to the mortals. Thus, fire was no longer the sole magic power of the gods.