they key to the article isn't the years covered but the fact that the Church wasn't suppressing knowledge which many people have an irrational inability to recognize.
The church wasn't suppressing ancient knowledge for the most part, but it wasn't exactly doing much to produce new knowledge, either. That didn't really get going (in Europe) until the Renaissance and Scientific Revolution, although there was some progress in the late Middle Ages as the article points out.
For the most part, the article is about preserving and recovering old knowledge. That the Renaissance had some precedent in the late Middle Ages is not exactly new, but it does tend to be forgotten in simplified accounts.
Right, the Church was actually in the habit of relying on "ancient" Greek sources, cherry picked to support various bits of doctrine or political stances. "Good learning" in the late middle ages meant learning these sources, which were already millenia old and long since surpassed by the Romans. But all that was lost and in the rediscovery of Western Culture that led to the Renaissance, the practice of building on more recent works, as well as reviewing ancient texts and ideas that had been dismissed by the Church helped begin the wave of humanism and inquiry that's defined Western thought since.
Albertus Magnus, Witelo, Robert Grosseteste (inventor of the scientific method), Roger Bacon, Petrus Peregrinus, William of Ockham: obviously these guys never existed, and the foundation of the Universities in the Cathedral towns never happened.
For the most part, the article is about preserving and recovering old knowledge. That the Renaissance had some precedent in the late Middle Ages is not exactly new, but it does tend to be forgotten in simplified accounts.