There are other names that have come up recently that were not in the article, the most prominent (so far) being Ron Turner, Tim Lewis and Chan Gailey. I'll comment here, briefly:
Lewis - It's not as though the Giants' defense has been anything special under Lewis. However, to Lewis's credit, they had steadily improved under his watch (until this year), and he ran a pretty good Steelers defense for four years prior. Like Rivera, he has no prior head coaching experience at any level, but has worked under Bill Cowher, so again, he at least has an idea of what a real head coach does. We could do worse.
Turner - I don't believe he's a serious candidate. The guy was an absolute disaster at the University of Illinois and the Bears offense has alternated between awful and barely respectable for most of his tenure. I've got to believe they're just talking to him to see how a real team works, and maybe to explore bringing him in as an OC/AHC if they hire Rivera as the head coach.
Gailey - This one seems like it's way out of left field, but maybe it shouldn't be. Gailey obviously has plenty of head coaching experience, and a well-earned reputation as a sharp offensive mind, though personally, I think that reputation should be tarnished a bit by his inability to make the greatest use of Calvin Johnson's talents. Gailey got a bum rap for his stint with the Cowboys, but they made the playoffs both years he was there, and that was clearly a team on the downswing anyway, thanks to Jerry Jones' meddling. And they really hit the skids after he left, with a trio of 5-11 seasons under Dave Campo. He's done a decent, but not great, job at Georgia Tech, with a 37-26 record, but they've lost a ton of big games (ACC championship this year, 0-5 vs. UGA, blew a big lead in this year's Gator Bowl vs. WVU). Still, the ceiling at Tech is probably limited, given that they'll always be #2 in that state to the Dawgs, and will always lose talent to other SEC schools as well, so Gailey probably shouldn't be judged too harshly for that. He's probably a better candidate than he's been given credit for.