Here is the conclusion of the passage that began at 2.42. For those whose hearts are captured by promises of enjoyment and power, and whose minds are swept away by flowery words — the resolute, single-pointed intellect that leads to samadhi simply does not arise in them.
This is cause and effect, stated without judgment. When the mind is scattered across a hundred desires — a bigger house, a more comfortable life, a higher position, the pleasures of heaven — it cannot settle into the kind of stillness that samadhi requires. Scattered water cannot reflect the moon clearly. Only still water can.
Krishna circles back to the idea from 2.41. There, he said the resolved mind is one and the scattered mind is many-branched. Now he shows what creates that scattering: attachment to pleasure and power. The diagnosis is complete. And the prescription is about to follow — in the shlokas on equanimity and selfless action that come next.