Great Levi Jackson card!
Bill Matthews ran track at NYU in 1951 as well, according to the NYU yearbook on Heritage.com, but I cannot find him in New York after, or at Michigan. He's not part of the 1952 or 1953 Michigan Wolverine rosters. Here's a strange guess, but is Bill Matthews the son of William Matthews who integrated baseball's Northern League in 1905? William also went on to be an influential Boston lawyer until his death in 1928. Are these two related? Both NYU and Michigan are known for their Law Schools. If so, to skip an NFL career to study and practice law is perfectly reasonable.
https://en.wikipedia.org/wiki/William_Clarence_Matthews