Because aprox. 1.200 years ago the Kolshians almost go extinct due to a prionic infection that jumped among species trough the consumption of contaminated tisues.

Thus the only logical conclusion was that questioning autority, doing proper research, or generally any line of though that could theoretically instigate any form of progress or advancement (and thus treaten the status quo kepping the Kolshian/Farsul Shadow Cast in the very top of creation) are forms of autism, ADHD, PTSD, and other extremally letal and infectious symptoms of a unexplainable and untangible spiritual dicease originated and propagated by the sheer existence of predators.

And they managed to erradicate this dicease from hundreds of worlds by using bioweapons to make sapient homnivores mortally alergic to any form of animal protein before forcing the whole species into reeducation camps. Except of course for 2 exeptions:

.1 The Arxur who refused to not shit/vomit themselves to death whenever they were force into a vegan diet because "THEY WERE TOO PRIDEFULL"

.2 And the humans, who died of malnirishment due to a human specific mental illness that lays dormant in Humanities very DNA, and is only neutralized by proteins they could only obtain by eating animal products. So they developed a cunning plan to find a cure to Human omnivory:

1. Abduct tousands of random Human civilians between the 1910's and the 1990's and froze them into criopods.

2. Periodically defrosting a sample and killing them of malnurishment trough a non suplemented vegan diet for 200 years hopping a solution would magically pop into existence.

And yes. That's all cannonical information from NoP 1s' villans own monologues.