Ryu didn't seem very surprised by this result.
When one faces a Dao so much higher than their own, it's very easy to be overwhelmed. Ryu's strike just now was like an information overload. Kaori was likely trying to process what was before her and exactly how to deal with it, but by the time she understood that it was far beyond her means to handle, it was much too late… Not that it would have made much of a difference.
To an outside observer, Ryu's blade would have seemed slow and overly simple. In fact, it would seem that way to Kaori as well. The trouble was that this would cause the dissonance to feel even worse. Kaori's instincts screamed that there was danger, but her mind couldn't process was it was because it was simply beyond her realm of understanding.