He was technically "qualified", but the bigger issue was that he didn't have the recruiting connections of somebody like Lamar Thomas. He is now just an okay high school coach 7+ years after the fact. The only thing he had going for him in that job opening was that he was a former player and he had a son that was a recruit. That's it. UK deserves better than former players with few recruiting connections, and Stoops must have thought so too. Again, an interview is a waste of everybody's time when you're not going to get the job from the outset.
Also, Russ is not a starter in the NFL. He started a few games for the Rams last year after they had injury issues, and then he lost that role because he wasn't good enough. He is barely hanging on to the practice squad of the Texans now because he was cut from the Cardinals practice squad about a month ago.