I would agree that they are powerless if indeed time stopped flowing and they ceased being able to interact with the world. They were powerful, they spent their power changing the natural cyclical state of the world into something that never changes, and now they are powerless because they are isolated- no power can or will ever be exercised again.
But what of a super-powerful being who comes and attempts to change or break it, and fails? I would argue that rather than the original cultivator having more power than the being, the being becomes powerless in this area. That is to say, power is situational and not transitive.
I disagree. In this situation where a being attempts to change the perfectly stagnant location, they wouldn't even be able to enter, as that would be a change to the perfect stagnation. So they would have to change it from the outside of the area, and they would fail in that regard. Is that being then powerless for failing to change the area of perfect stagnation? No, they can still do other things, they still have their abilities, authority, wealth, connections, skills, etc. All of that is simply ineffective against the hypothetical perfect stagnation.
My argument, more succinctly, is that being unchanging is a source of power, even if you are no longer able to effect change yourself.
Using that elaboration, someone with a way on stagnation still has power because they're resisting change and pushing the world back.
That being said, I do agree that it works well as springboard. As I said earlier in this post, I hope LQ takes that definition of power, but I think it's unlikely that she'll copy it word for word or take the same understanding as Shenhua.
See, that elaboration, to me, highlights the issues with the proposition that "Power is the ability to effect change" rather than resolves them.
The question becomes, should we take Shen Yue's statement as true that the ability to effect change = the ability to resist change? This is vital as the only way the proposition "Power is the ability to effect change" works is if the ability to effect change = the ability to resist change.
So, are there other ways to phrase the idea that "the ability to effect change = the ability to resist change" that would be substantially similar, but cause questions as to its authenticity? Well, let's look at this, "The ability to overcome inertia = inertia."
To me, "the ability to effect change = the ability to resist change" is substantially similar to "the ability to overcome inertia = inertia." Inertia is the ability to stay the course, to be the same. To change something, you need to be able to overcome that thing's inertia.
Now, to me, it is much tougher to sell as true that the ability to overcome inertia is the same as inertia. One requires an external force while the other is a natural product of existence. To say they are the same thing does not ring true to me. This leads me back to not believing as true Shen Yue's elaboration on her statement to justify the proposition that "Power is the ability to effect change." And a less hypothetical example of my issue with Shen Yue's proposition is a pebble.
A pebble has no will, it has no ability to effect change in the world around it. However, it is able to resist change to it, at least for a little while. Despite the insistence of wind and rain, the pebble will remain a pebble for some time, and in this way, it is resisting change. According to Shen Yue, this is power, the ability to resist change. But, if it has power, it should be able to effect change. Yet a pebble can not, it does not have the will or ability to change anything about itself or the world around it.
So, according to Shen Yue's elaboration, the pebble has power. Yet, according to the proposition originally proposed, "Power is the ability to effect change," the pebble shouldn't have power. And that creates an issue. Is the elaboration a better statement on the nature of power than the proposition it proposes to elaborate on? I think so. And this also means that I don't think Shen Yue's proposition "Power is the ability to effect change," is true.