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Hi John.  In answer to your question about why the UPenn study is inappropriate for the article, I'm reposting a quote from WP:MEDRS: ""any given primary source [such as this study] may be contradicted by another, and the Wikipedia community relies on the guidance of expert reviews, and statements of major medical and scientific bodies, to provide guidance on any given issue."" 
When I first read  statement, ""We do not use primary sources to refute secondary ones,"" I was pretty confused.  I mean, primary sources are more fundamental, right?  Well, the idea is just that when the ""secondary source"" is a systematic review or the like, what that means is that the secondary source has looked at the all primary sources and evaluated their significance and rendered a scientific judgment.  The authors of the secondary source are better able to interpret the primary sources, not only because they are collecting those sources and considering them in the context of all the available evidence, but because those authors are experts in their fields.  We should expect that they understand the data better than we do, or, at the very least, better than the average reader.  Interpreting primary sources is challenging, and when the experts have already done it for us, there is no reason to foist that responsibility on the average reader. 
From my perpsective, the issue of whether it's a press release or a peer reviewed article quoted to describe the UPenn/Philadelphia study is more or less a red herring.  That study is just a single study, and we should trust the public health experts to render judgment rather than ourselves or the readership. I hope this helps answer your question.   "