Well dozens of other colleges are getting the players now that would have gone to Nebraska 20-30 years ago.
Yeah he's right, and you're right too. They are hurt by being in a state with very few legit D1 prospects, and the closest states with potential recruiting grounds are a long ways away. So it helped when they played in Texas a good bit, by virtue of their Big 12 membership. But as others have mentioned, the whole Prop 48 was truly what gave them the ability to be an elite program for so long. They got a lot of guys out of Florida, California, and Texas that couldn't get enrolled at other places. When they lost that, they slowly began to fade away. And I do mean slowly, as they did win one NC and still competed at a pretty high level after joining the Big 12 until around 2002 or so.
But now, they regularly play in Iowa/Minnesota/Wisconsin. All states with little more talent than Nebraska has. They are in the wrong side of the Big Ten, as far as recruiting goes. The majority of talent that exists in the B1G footprint lives in Ohio, Pennsylvania, and Maryland. I guess New Jersey counts as well due to Rutgers.