While this might sound like good evidence to support increasing your protein intake to build more muscle, it doesn't take into account the adverse effects of protein intake above the RDA of ~0.8g/kg of healthy body weight, unless you're over 65.

> The adverse effects associated with long-term high protein/high meat intake in humans were (a) disorders of bone and calcium homeostasis, (b) disorders of renal function, (c) increased cancer risk, (d) disorders of liver function, and (e) precipitated progression of coronary artery disease.

- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4045293/

High protein intake is associated with elevated levels of IGF-1, and "High IGF-1 levels increased the relationship between mortality and high protein":

> Respondents aged 50–65 reporting high protein intake had a 75% increase in overall mortality and a 4-fold increase in cancer death risk during the following 18 years. These associations were either abolished or attenuated if the proteins were plant derived. Conversely, high protein intake was associated with reduced cancer and overall mortality in respondents over 65, but a 5-fold increase in diabetes mortality across all ages.

> These results suggest that low protein intake during middle age followed by moderate to high protein consumption in old adults may optimize healthspan and longevity.

- https://www.cell.com/fulltext/S1550-4131(14)00062-X

Also important to note that one of the authors of the OP article is an employee of FrieslandCampina, the world's largest dairy co-operative and one of the top 5 dairy companies in the world.