I think you're conflating whether or not there's correlation/causation with whether or not the result is significant. If a stock appreciates or depreciates at the same time that something related to that stock happens, a relationship between the two is not an unreasonable hypothesis.
Of course, there's still the matter of actually validating that hypothesis, and examining whether said hypothesis actually holds true or the coincident timing really is just coincidence and nothing more (or, indeed, if the timing really was coincident between the two events, e.g. whether or not the stock move happened before the event that allegedly "caused" it).
And of course, even if the event did cause the stock move, that's still a separate concern from the long term impact of that stock move. It could very well just be a temporary blip, or it could be a harbinger of some more significant change.
Of course, there's still the matter of actually validating that hypothesis, and examining whether said hypothesis actually holds true or the coincident timing really is just coincidence and nothing more (or, indeed, if the timing really was coincident between the two events, e.g. whether or not the stock move happened before the event that allegedly "caused" it).
And of course, even if the event did cause the stock move, that's still a separate concern from the long term impact of that stock move. It could very well just be a temporary blip, or it could be a harbinger of some more significant change.