[math-fun] speed of light may not be constant?

http://blogs.voanews.com/science-world/2013/03/26/speed-of-light-may-not-be-... described latest science fad claim that light's speed may fluctuate in space and time. Does this contradict the observed fact that light from halfway across the universe, hitting the left side of your telescope mirror, is still perfectly in phase with light hitting right side of your telescope mirror, allowing interferometry?