Yes just because there is a paper suggesting they have found all the answers doesn't mean they actually have, especially when it is in a journal with a impact factor of 4. It sounds like a bold claim, I am suspicious of bold claims, if it really were true why has the paper only been cited 30ish times since 2009? There is a paper in some journal on everyone's favourite crackpot theory, but only a extremely small fraction of these will stand the test of time.

The gut microbiome is a hot topic at the moment, but like the author says we have no idea how to safely harness this as a therapy in a clinical environment. There are a lot of theories. The internet is full of snake charmers of people suffering from ill health, I have been victim of a few myself, this is why we have to enquire very deeply into everything, and ask ourselves is this really sensible or am I being misled?