There could be officiating bias for a lot of reasons, none of which have anything to do with some conspiracy against Nebraska.
Officials are human and they have normal human traits. Some of them, maybe even whole crews, just don't like Nebraska's coaches. Or they like the other team's coaches more.
Maybe they love their conference and deep down feel like Nebraska is still not a real part of the conference.
Maybe they feel like Nebraska & Nebraska Fan is arrogant and that rubs them the wrong way.
Maybe they feel like Nebraska places undue blame on the refs and they should clean up their own play first.
Maybe they got booed at by the fans at Memorial Stadium and they felt that was unjustified.
There's a ton of reasons why they may call more penalties on us than we actually deserve, or fewer on our opponents. None of those reasons requires overt bias. None of them involve conspiracies.
I've heard versions of every one of those examples from fans of other teams. If those fans have those thoughts, why can't the refs? They're humans, too.
Ask Penn State Fan if they felt like they were immediately accepted into the Big Ten when they joined 25 years ago. Ask them how long it took for them to feel like the rest of the conference accepted them, including the refs.