I would encourage him to stay put. While 64 of age isn't considered old for the most part. His body is. Why start over again with all this NIL money hindering progress of what you're building? Unless he really loves the city, school, perhaps would like to retire there, etc., I'd stay away.
Just because other coaches don't believe in the word loyalty, that doesn't mean that Fleck has to lower his standards. I commend Fleck for doing the right thing.