have anywhere near the credentials of the author, Dr.
Argumentatum ad verecundiam. My wife's a research scientist, D.Sc.(tech), and whenever we want to keep meetings with investors, partners, associates, clients etc. short and sweet, we'll just let her do the talking. She's not questioned much if at all even if she presents my projects and develoments. The fallacy of credentials/authority works fabulously even when you're presenting facts and not just speculations.
The motive behind attacking meat and dairy is and has always been rather ideological. Desired results are usually determined beforehand, which manifests itself in cutting corners by overlooking the distinction of what the actual consumed food products are, their content, additives, processing and a plethora of factors which absolutely would require a controlled environment. For instance, even without reading the report in question, I'd hazard the usual guess: has the author really fed the research group unprocessed (as a reminder: this is hunting forum) meat and dairy products, as they are, or drawn conclusions from uncontrolled diets consisting of processed animal proteins, unknown quantities of sugars, nitrites and so forth, and having kept a control group on a strict deprived diet, from a statistically identical starting point?
I thought not. A research experiment like this is extremely difficult to arrange and I'm aware of none ever attempted or completed. If you are, please let us know.
From a purely causal, scientific and nutritional standpoint, the vegetable-based diet and "health" fallacy has all the characteristics of a placebo/nocebo experiment by disregarding a number of factors, the most critical being not just protein sources but the whole composition of what's being consumed. Switching from highly processed sausages, cheap hamburger steaks (you know the type, one falls behind a fridge, you find it three years later and it hasn't grown any mold), associated bakery products etc. to any non- or even less-processed, more or less additive-free food will definitely yield health benefits.
People are intentionally led to believe that it's something you eat instead (vegetables), disregarding all the additives, preservatives and sugars you give up at the same time. Nocebo in its purest form, causality being obscured by propagandist methodology. You might as well eat more or less as much as game meat, pork, beef, chicken and fish as you like, and physiologically speaking, be even healthier with fewer risks of nutritional deficiencies.
Because this conversation seems to be well past its "best before" -date, I'll play the dreaded H-card to finish it off. The lean prototype of Übermensch was to be created with vegetarian diet adored and practised by the great leader of the Reich, who himself had messed up his digestion as a direct result of it, and the only viable method to keep slightly malnourished forces operational was a liberal dosage of methamphetamines. Not that the ideologically and politically suppressed meat and dairy industry would have been able to supply the demand had it been allowed to, but as an experiment to dictate what a good german from Bund Deutscher Mädchen to Arbeitsfront and what was being served at all Kraft durch Freude events, it failed miserably. Because of straightforward nutritional facts that can't be overcome without an extensive, worldwide trade, import and preservation infrastructure, which didn't exist back then and in today's terms is against all the principles vegetarian diet is hyped with.
So there. Food for thought. Sorry about the long post, in case of TL;DR.