They aren't talking about neutrinos getting to the detector faster than some particular photons going through a medium. They are talking about C, the speed of light in a vacuum.
Well, this part of the article suggests they ARE comparing it to the speed of light in the medium:
“Light would have covered the distance in around 2.4 thousandths of a second, but the neutrinos took 60 nanoseconds - or 60 billionths of a second - less than light beams would have taken.”
Might just be a poorly written article though.