In 2005, the below paper was published showing life extension in mice allegedly due to methionine restriction.

So the instant article would make it appear that at least some scientists think they are closer to showing a similar mechanism at work in humans.

From 2005, "Aging Cell" journal:

http://www.ncbi.nlm.nih.gov/pubmed/15924568

Methionine-deficient diet extends mouse lifespan, slows immune and lens aging, alters glucose, T4, IGF-I and insulin levels, and increases hepatocyte MIF levels and stress resistance.