I have not read the article. I have read US news rating of colleges.
I would say UW, Illinois Maryland, Missouri, Rutgers, Florida, Penn state, Duke, UNC, Georgia , Washington, Notre Dame, Ohio St, Texas, Texas A&M, Vanderbilt, the Air Force Academy, and Iowa are academic peers of Purdue.
my opinions are based on the US news and Forbes report of college ratings and also by where the local academic scholars all chose to go to school. and the placement of their graduates.
I would place the Ivy League, Northwestern, Michigan and Stanford as slightly above Purdue.
i would place all the rest as beneath Purdue.
Purdue is known for its engineering programs, but it has an awesome management program, pharmacy, vet school, ag school, and science/math/it programs. I may be a little critical at times of Purdue athletics, but I would place their academics in the top 20 just below the Ivy League .