Trespassing is not a right to free expression.
The schools own their athletic facilities and have full right to limit access to them as they see fit. If the conference says you must keep spectators off the field in order to receive funding from the conference, you better believe the schools will prohibit spectators from accessing the field. The conference, with its purse strings, can provide a hell of an incentive for member schools to stop spectators from storming the field.
The conference, with its purse strings, .....”
Some of these highly rated teams could easily follow the Neuter Dame model and go independent. Storming the field should be a right of passage. It has been done throughout history!!
I had a front-row seat to hearing this explained to a particularly unruly fan about 35 years ago. This fan was part of an unruly group of middle-aged, opposing fans sitting right in the heart of season-ticket holders section. Initial pre-game banter turned ugly quickly and I was surprised that fights didn't break out. Right before halftime, a large contingent of security guards appeared, led by a deputy sheriff. The group was informed by the deputy that they were being re-seated (to comparable seats right behind their team's band).
Turns out the particularly unruly fan was a thoroughly-drunken attorney. Go figure, huh? You can imagine the A-hole-ness level here. After listening to the profane rant from the attorney and the threats of all the legal avalanches coming, the deputy calmly responded. He informed the attorney that because of his profession, the attorney knows that the deputy was operating within the law. He told the attorney that he could leave the stadium or go to his reassigned seat but if he tried to return to his current seat, he would be arrested and charged with disorderly conduct. He would be handcuffed, taken to the holding cell at the stadium and because it seemed apparent that he was drunk, he would have a breathalyzer sample taken at the cell and his possessions would be searched looking for alcohol because some security guards had seen him drinking from what appeared to be a liquor bottle. Alcohol was prohibited in the stadium. At that time, additional charges could be added and/or the initial charge could be upgraded. He would appear in front of a judge before the day was over.
At this point, he became quiet and some lady (probably his wife with his possessions) quickly took him by the arm and led him away. The deputy followed him out to applause and high fives. The group did go to their reassigned seats and the guy looked like he passed out a while later.
The university owns the facility and can make reasonable rules. Violating them can have legal ramifications as I learned that day.