Unfortunately, it was a ‘deep critical thinker’ who had come up with this idea in the first place.
That ‘if you want to control, you need to isolate the intellectual’.

A ‘plain-clothes man’ doesn’t think in these therms!

Let me rephrase the whole thing.

I am rational.
Which means that all my conclusions are valid. Simply because I have reached them in a rational manner.
Hence all other conclusions are wrong. For the simple reason that they are different from mine.
Since they are wrong, they should not reach their audience.
For they might displace my conclusions from the public mind!
Which brings me to the conclusion that if I want to conserve my position – as the official thinker – I must make it so that all other intellectuals must be isolated from the public.
Only I need to dress up this conclusion as if it was about the greater public good.

And this is why Protagoras of Abdera and Socrates had been banished from the forum.
Why Plato maintained that before being allowed to rule the philosopher-kings had to be specially trained for the mission. Taught to keep an open mind towards alternatives!
Why Marxism, Fascism and all other authoritarian lines of thinking lead those who pursue them into the same dead-end. Into abject failure…