What is wrong with Richard Davidson’s meditation research project?

20 years ago Richard Davidsons group published a paper in PNAS about meditation: https://www.pnas.org/doi/10.1073/pnas.0407401101 From which Matthieu Ricard said, it might be revolutionary, and he hoped that it would be pusblished in Nature. Later on, Matthieu Ricard, Buddhist monk with a PhD. in cellular genetics who participated in these studies gave further talks about this …