As for honing their twisted hearts.
It is because they are no longer cultivating those Demonic Cultivation Techniques, so their hearts will no longer continue to become evil!
And this situation can be slowly restored through mental training!
The most important thing is that their hearts were twisted due to the Cultivation Technique, but now, they no longer have the technique to torture them, making them more twisted. Even without honing their minds, they can slowly recover over time, returning to their original selves.
However, if you originally had a narrow or dark mind, even if you undergo mental training, it at most prevents you from continuing to harbor evil thoughts.
