Think about it this way, if you allow spirits to have their own growth, ecology and society even at the cost of uncertainty or chaos for mortals (that Cultivators will have to deal with), why, that's the Weilu way of doing things, a stated goal that is close to the heart of our protagonist.
Sealing off the mountain tops and dusting your hands while saying "job well done, peace for a thousand years" is the Peaks/Imperial Way of doing things.
Hence, I am compelled by narrative to vote:
[X] Allow Hanyi to do as she has said. (Risks of future changes to winter ecosystem, ???)