As a former medical researcher, I do have some knowledge of Pubmed.
Pubmed is simply a library. It indexes articles published in a large number of peer reviewed journals. Once the journal reaches the criteria for inclusion in Pubmed, there is no screening of individual articles by Pubmed.
This article has been published in the journal
Alcoholism: Clinical and Experimental Research, which is the official publication of the Research Society on Alcoholism and the International Society for Biomedical Research on Alcoholism. While I never had occasion to use this journal during my career, my expectation is that the peer review would be rigorous.
Alcoholism: Clinical and Experimental Research - Author Guidelines - Wiley Online Library
The current impact factor of this journal is 3.21, which is good.
https://www.researchgate.net/journal/1530-0277_Alcoholism_Clinical_and_Experimental_Research
I am not going to purchase the full article and critique it for you, but let's assume that the study was well executed. From the abstract, we can see that the study examined several chemical variables at the time of autopsy, and correlated them with history provided by relatives. Now, it's a good thing that the study involves humans rather than experimental animals, but, as we all know, history can be subject to bias and inaccuracy. Also, there could be many other variables which influence the results. Correlation is not the same as causation.
The study investigated the association between consumption of different alcoholic beverages and β-amyloid (Aβ) aggregation in the brain, 1 of the neuropathological lesions of Alzheimer's disease. The results suggest that there was, indeed, an association between these variables.
BUT this tells us nothing about any association, causal or otherwise, between beer drinking and Alzheimer's. That is a question that this study was simply not designed to answer. Rather, the results of this study have generated some interesting questions, which can only be answered by further research.
As a scientist, my response is that the findings are interesting, but the level of evidence in this study does not allow us to conclude that drinking beer is protective against Alzheimer's.
John Oliver's monologue, by the way, is spot on!