I would argue with these tweets to say that I would be absolutely shocked if UNL has not already looked into this. A statement such as "we have not had a chance to review the charges" would be accurate since there are no charges yet. A school the size of UNL and a program such as this would not sit on their hands if they had been contacted by the AG's office and the police. Especially for a star athlete.
I work at a school with a relatively small Title IX office where the athletics are bupkis compared to Nebraska, but even so, there is an agreement between the student conduct office and the athletic department to make each other aware of any issues that even remotely have the potential to cause problems. In addition, there are regular meetings between everyone on campus who touches Title IX related issues to be aware of any new situations so they can be addressed. Any rumblings of anything like this, and a lot of mechanisms start running.
So let's say in this case they heard something from the AG, or the police, or from a lawyer, but did not have any details and did not even know it had anything to do with sex, a hell of a lot of questions would have been asked in order to get to the bottom of it. At the very least, the university would want to put themselves in a legally defensible position and try to stem off any bad PR, even before trying to protect the athlete or the coach. UNL has a big Title IX office, and a big General Counsel office, and a lot of people whose jobs deal in PR, not to mention the size and influence of the athletic department and football team. I guarantee they have pulled all the stops in addressing this situation long before it came to light this morning.