I suspect he means that light maybe travels slightly slower than the constant c used in relativity. Maybe photons actually have a really tiny rest-mass. Maybe our measurements of the speed of light are all in non-perfect vacuum which makes it slow down a little bit.
If they had tiny mass, we would observe variance in measured values of c, since less energetic photons would move slower. Measurements of c have relative precision of at least 10^-7 and no dependence on energy has been observed in the vacuum. Therefore the measured speed of light doesn't differ from the relativistic c more than by 10^-7. The relative difference which is reported in the neutrinost seems to be 10^-5.
http://www.nature.com/news/2011/110922/full/news.2011.554.html
http://arxiv.org/abs/1109.4897v1
http://usersguidetotheuniverse.com/?p=2169
http://news.ycombinator.com/item?id=3027056
Perhaps the end of the era of the light cone and beginning of the era of the neutrino cone? I'd be curious to see your probability estimates for whether this theory pans out. Or other crackpot hypotheses to explain the results.