Who was the last kid that it came down to Oklahoma and ND to the end? Caleb Kelly? Kelly didn't even make it in the NFL not sure why but no idea what he currently is doing. Also ND has had a better track record for safeties getting to the NFL as of late.
I don't think ND's track record for defensive backs is really something you can hang your hat on, if you go back over the last decade. Hamilton was a great player, and is recent and fresh in the minds of both fans and recruits, but he's predominantly an outlier. ND has only had four safeties drafted in the last ten years, five if you include Julian Love, who transitioned over after his first or second season in the pros.
It does help your argument that Oklahoma does not have many safeties in the NFL, and those that are, are not household names. The only one I can think of is Tony Jefferson, who was undrafted about nine or ten years ago.
95% of the time, a great player will always find his way to the NFL, regardless of which school or which coach he played for. I don't believe Bowen is looking at the NFL success of safeties from each school - if that were the case, he would have looked more at Alabama, LSU, Georgia & Ohio State.
It is either that he wants to stay closer to home, or spend three to four years in South Bend. Coupled that with NIL oppourtunities and/or guarantees, his decision will come down to what he believes to be the best fit.