I mean Glenn is a defensive minded, young, and hungry coach who is a leader of men type like Rizzi. So, I don't think he's the opposite of what you want, he's just a defensive coach instead of an offensive coach. I too would prefer a young offensive coach, but if you can't get the right offensive coach, I would go with Glenn over Rizzi since then you know at least one side of the ball is covered. And Glenn is a former player and likely just as much of a leader of men as Rizzi. Maybe even more so since as a former player he understands how things are from both the perspective of the players and coaching staff.
That being said, I would like the Saints to take a long look at Kliff Kingsbury. I like Ben Johnson, but I think he goes to the Bears or the Bengals. Kingsbury has done a great job with Jayden Daniels and I think he got kind of a raw deal after one bad season with an injured QB in Arizona. Before that he was steadily improving a team that started off as terrible. But there are rumors he is going to Chicago.