The author used three ILBs who were drafted in the second round, are one or two years younger than Littleton and became full-time starters right out of college, except for Smith who was hurt and became a starter after red-shirting his rookie year. Not good comps, IMO.
Eric Kendricks with Minnesota and Benardrick McKinney with Houston both signed extensions in 2018 for 5 years, $50 million. Others like Anthony Hitchens with Kansas City and Jordan Hicks with Arizona signed for less money per year than Kendricks and McKinney.
IMO, Littleton is more comparable to the group of ILBs I listed not the author's list.