So I think the important thing here is how this waterfall is being explained to visitors. If it's open information that the waterfall only flows naturally in certain months and is artifical in others and people still want to see it when it's artificial that's fine. However it seems this is being sold as a natural waterfall when it's artifical part of year which is the problem.

Bases on thr park's comments, it seems the move to make it artifical part of the year stems from their lack of openness that it only flows naturally part of the year. In comparison, Yosemite National Park (US) has a whole web page explaining when the waterfalls flow and the peak months to see them. https://www.yosemite.com/yosemite-waterfalls-spring/?amp=1 In my opinion, his park should be more open about the natural flow months so visitors can choose when to visit.