It's not clear to me (because that bulletin was in Gov-speak and therefore pretty impenetrable), but my best guess is that the concern derives from this section of the bulletin: While requiring the agency to select reviewers with x, y, and z qualifications (all which seem to be perfectly fine qualifications, by the way) it doesn't seem to provide any process for ensuring this happens in a verifiable way. Thus (if I read this right) it relies on the competence, good will, and disinterest of the agency seeking to get its policies vetted to choose to be among those who will do the vetting people who might very well rip their policies to shreds. Sure, it could happen. It also specifically excludes some categories that would contain many of the most experienced, heaviest hitters and most impervious to political pressure. Anyway, there's little wrong with peer review (relatively speaking) and a lot right about it, if properly implemented. The trouble with this version is there seems to be a loophole that will allow agencies to acquire for their policies the veneer of scientific validity without the substance, should that be what they want.