I've read some accounts of the relationship between the Khmer Rouge and China. However, I've never come across this claim before, asserted by a user in askreddit:
He [Pol Pot] was acting on behalf of China, not Cambodia. He didn't see Cambodians as his own people. His plan was to settle Chinese colonizers in the ghost cities.
My instinct, as with most unsourced claims on the internet, is to ignore and move on. But I'm still intrigued on the off-chance that there is a grain of truth in the claim.
Can anyone provide any more information about this or is it complete bunk?
Its completely bunk because the Khmer Rouge actively went after the pre-existing Chinese minorities in Cambodia. The Chinese in Cambodia were mostly urbanized merchants and traders which made them enemies in the eyes of the Khmer Rouge as symbols of the old order and class enemies. Not only that but Pol Pot did not see ethnic minorities as compatible with his vision of agrarian purity and in a decree simply outlawed the existence of Vietnamese, Chinese and other ethnic minorities in the country. The Chinese language was banned as well.
As such the Chinese were one of the worst hit groups in the Cambodian genocide. Out of a population of 425,000 in 1975, only around 200,000 were still alive by 1979.