[naasking]

From your link, "the subjects consumed 1,823 calories on average per day, of which the majority came from carbohydrates (51%), followed by fat (33%) and protein (16%), with most of it (11%) derived from animal protein. The percent of calorie intake from protein was used to categorize subjects into a high-protein group (20% or more of calories from protein), a moderate-protein group (10–19% of calories from protein), and a low-protein group (less than 10% of calories from protein)."

Strange, that doesn't seem like a high protein diet to me. Athletes, particularly resistance trained athletes, regularly consume 30% or more of their calories in protein.

Further, from your link, "These associations [of protein -> higher mortality] were either abolished or attenuated if the proteins were plant-derived." So protein itself is not the problem, despite the study's authors repeatedly asserting this.