This idea is a trivial extension of object permanence.
Object permanence is the understanding that objects continue to exist even when they cannot be observed (seen, heard, touched, smelled or sensed in any way). This is a fundamental concept studied in the field of developmental psychology, the subfield of psychology that addresses the development of infants’ and children’s social and mental capacities.
Object permanence is an internalization of naive philosophical realism, which is the understanding that stuff exists beyond what our minds are currently perceiving (the other possibility being The Matrix, where the external world only exists as an extension of the mind’s processes).
Rather than speaking only of physical noumena, we might consider whether a similar psychological mechanism exists for phenomena.
Thus, we shall say “concept permanence” is the internalized understanding that there exist ideas and concepts outside of what is currently being thought by human minds. Most mathematicians are Platonists of this sort. They generally believe that math is discovered and not invented, and that mathematical ideas can exist, be valid, and be true without anyone knowing it. One does not “create” theorems, but rather “discovers” and “proves” them.
I believe this faculty (or facility, at least) is not present in extraverts and neurotypicals to the same extent as it is in introverts and people with Asperger’s syndrome. Perhaps it is not present at all in those personalities driven to censorship, who care so very strongly a priori about the thoughts and opinions of others. Thus, it makes perfect sense to an ordinary person that “bad” ideas ought not to be even held in the fore of the mind, much less spoken aloud (which risks spreading the ideas to others, as well as inevitably bringing the idea to the fore of the mind).
Furthermore, I believe that this tendency may be explained by evolutionary psychology (of which I am usually skeptical). It is certainly true that the safest way to ensure a particular thought does not have any effect on human affairs is to exterminate anyone who has had it previously. “Two men can keep a secret if one of them is dead.” A strong argument can be made that some knowledge, such as the knowledge of how to breed a biological weapon of mass destruction, ought to be suppressed by law- with the overwhelming threat of government violence. Suppression by force is not a guarantee that the idea will not be rediscovered, but within the normal human range of intelligence it is a near guarantee (i.e. good enough for government work).
Thus, I believe large societies naturally select for conformist personality types that lack the facility to develop concept permanence.
It has been noted by many others that the modern belief in “science” amounts to no more than dogmatic faith in the scientific profession and body of knowledge. This modern faith could be reasonably described as “scientific idealism” (as opposed to scientific realism). So it makes perfect sense to ordinary people (who by and large subscribe to this faith) for “bad” science to be suppressed, rendering it effectively nonexistent within the human memetic network, and more importantly (to utilitarians) suppressing its influence on human affairs.