Thanks Lal for your thoughts.
It seems to me that we have to strive hard to stop attachment from doing dasa akusala and cultivating bad gathi at first, and then strive hard to do dasa kusala and cultivate good gathi.
As beings’ asavas weaken and are eradicated, eventually they even come to realize the futility of being attached to doing good (for even kusala/punna kamma brings with it vipaka that has viparinama nature). Doing good just comes to them naturally, without prompting, and they do it without even a subtle bit of craving for rewards when they achieve Arahanthood. I guess this is the bodily part of what is meant by giving up attachment to the Buddhadhamma in order to attain Nibbana.