Gravity Wave 'Smoking Gun' Fizzles

Gravity waves of curvature made in cosmic inflation will polarize the real photons in the cosmic background microwave radiation from 380,000 years after the hot Big Bang, however:

"Gravitational Radiation Can Be Produced More Than One Way
ScienceDaily (Apr. 17, 2008) — A team of researchers from Case Western Reserve University has found that gravitational radiation—widely expected to provide "smoking gun" proof for a theory of the early universe known as "inflation"—can be produced by another mechanism."

There is a serious conceptual error made by the science journalist in the article. See if you can find it.