Namath is a weak HoF member, but I don't put that on TD/INT ratios. Back in the old AFL, nobody had great TD/INT ratios. The year the Jets won it all, 7 of the 10 teams in the league threw more INTs than TDs. Of the most successful QBs in the '60s AFL, only Dawson and Griese had positive TD/INT #s. Guys like Jack Kemp, John Hadl, Daryle Lamonica, Babe Parilli... all negative ratios.
Namath's thing was basically going Air Coryell well before Air Coryell was a thing. Was the first to 4K yards passing. He went for big chunks. He had two short white guys (Maynard & Sauer) he turned into leading receivers. He was drafted as a dual threat guy - he could run at Alabama - but had to learn how to be a pocket passer in the pros.
He was a better QB and leader than given credit for today. But under today's criteria, he's nowhere near a HoF. He's kinda like Dave Parker - had a brief time on top, but most of his career is mediocre or worse. If he didn't win that SB or get named MVP for it (and for the league in general), he wouldn't be in Canton.