Is assuming the audience has knowledge of fundamentals or the intellectual curiosity of their own to pursue it wrong? If every article had to describe the most basic aspects of physics, they would be books and significantly harder to understand due to breathiness.
If it was written for scientific audiences it would use proper terms instead of factually wrong "light slows down". It's not "easier to understand" when it is wrong. Speed of light does not change.
The speed of light in a vacuum does not change. The speed of light in a non-vacuum medium can be different than the speed of light in a vacuum, however. And light passing from one medium to another changes speed (and is refracted). See https://en.wikipedia.org/wiki/Refractive_index
Weird, those of us who knew what refraction was knew what they meant just fine. Saying light "slows down" in alternative mediums is the normal way to communicate it.
