Yeah, stories like this are garbage. Nobody knows why day-to-day fluctuations in the market happen. (Mostly.)
It doesn't mean that the reaction is correct or that it won't be undone in the future. But there's a huge difference between "day to day fluctuations are unpredictable" and "day to day fluctuations are inexplicable."
The reality is the markets react to thousands of individual factors and often small changes lead into positive feedback loops. So, while the timing may be explained by some news breaking the magnitude of change is generally influenced by all those other factors.