I skipped every response to the OP because it's an absurd premise. Guess what? There's no guarantee Schiano would be a home run. He is not some kind of default option. He didn't work out in Tampa Bay, his defensive coordinator work at Ohio State was not exactly stellar, and he's 20 years older (wiser, perhaps, but as energetic?) than he was the first time. A first time that was remarkable for a while considering what he walked into, but it's not as if he won two conference titles and built upon that amazing 2006, which, again, was built on a couple of guys who bailed on another school when it fired the coach.
The athletic department has to answer for any hire that does not work out. Period. There is no need to answer "Why not Schiano?" He doesn't have some bizarre divine right to the job. If they get this wrong, it is independent of why they didn't bring back Schiano. This is not the president or AD who hired him and they owe him nothing.
And if you people are Schiano fans and not Rutgers fans, just leave now and stop wasting our time.