Actually, it's an interesting test on its own. It may have accidentally exposed a bias in editorial choices. In fact, if the journals do put any weight on source of funding of the research, can they claim to be "peer-reviewed"?
It would mean that they only give partial consideration based on the peer reviews and give some of consideration's weight to a source of funding.
Further, a case can be made that any journal that requires that all sources of funding be disclosed and yet does not make this requirement clear to its subscribers (and still maintains that it is a "peer-reviewed" publication) is a journal that is committing fraud. By making disclosure of the sourcing of funding a requirement, it makes it part of a pre-screening for review. So it gives some however-justifiable or however-little weight to a consideration which has nothing to do with peers' view on validity of the research.
Research should be considered on its merit.
is not being naive because of the very sentence that follows it:
The assumption should be made that there are vested interests on both sides of any controversial scientific issue and the source of funding should not be considered as a data point in evaluating the legitimacy of research
Waste not, get your budget cut next year.