There is a huge difference between ’the author believes’ and ‘this evidence supports’. The important bits of scientific research is the evidence not the scientists conclusions.
If an existing test was not sensitive enough to detect some effect, any conclusions from that data are effectively worthless. However, the test still provides an upper bound for the magnitude of an effect.
Authors rarely limit themselves to only the evidence gathered from a single study when making these conclusions. I have even seen many conclusions not particularly supported by the evidence presented.
