These are among the sternest words in the entire Gita. Krishna speaks in the first person: I myself cast them — these hateful, cruel, lowest among human beings — into demonic births, again and again. The word ajasram — repeatedly, ceaselessly — makes it clear this is not a one-time consequence. It is a cycle.
The language is severe. Naradhaman — the lowest of humans. Kruran — cruel. Ashubhan — inauspicious, sinful. Krishna does not soften these words. The severity matches the gravity of the offense: despising the divine, harming others, and living without any moral compass.
Yet this is not revenge. This is the law of karma operating through the Lord's governance of the universe. The seed determines the fruit. A person who cultivates cruelty and hatred will find themselves in circumstances that reflect those very qualities. Krishna is describing the mechanism, not expressing personal anger. The statement is a warning, not a curse.