It's a proven technique that's worked in the past.

The Irish Potato Famine.

The 19th Century Climate Famines in India, Egypt, Sudan, Brazil, China, and Indonesia.

The Soviet Famines

The Killing Fields of Cambodia

Using starvation and "work camps" to get rid of your social enemies is an old practice.

What the historical evidence indicates.

Is that a culture can rapidly lose about 50% of its population without COLLAPSE.

Beyond that, fragmentation and reordering start overwhelming the stabilizing effects of cultural inertia and normalization.

There are LOTS of examples of societies surviving 50% "die-back". There are none to few examples of societies pulling through when die-back exceeds that threshold.