Frazier knows defense, but he was a mediocre head coach 10 years ago. I don't see what he's done to earn a retread gig.
I don't know the details of Rooney Rule compliance (how many minority candidates do you have to talk to? who qualifies?), but Frazier doesn't seem like a serious HC candidate at all. I think Jerry would literally hire Jason Witten before him. If there's any chance of this happening, I suppose it'd because Frazier would be the sort of "just glad to be here" puppet HC that Jerry craves.
I also agree that he is the kind of low profile ball-knower that you'd want to have at DC while "Coach Prime" grabs all the media attention.