I always thought that was an informal rule, a sort of word to the wise. If the police get involved, it must be an official thing. This news from Radio Online...
"WWL-AM/New Orleans LSA pre-game co-host Bobby Hebert was kicked out of the Tiger Stadium press box in Baton Rouge for cheering during the fourth quarter of Alabama's 21-17 victory against the Tigers last Saturday evening, reports The Avocate. LSU spokesman Herb Vincent confirmed to the newspaper that campus police asked Hebert to leave after repeated requests that he stop cheering, which is forbidden in the press box.
"We got some complaints from some reporters around him that he was cheering in the press box," Vincent told The Avocate. "So I asked him to tone it down. I continued to observe him, and I asked him again, and he said he would comply." Hebert didn't comply after three warnings and after the last LSU touchdown drive in the fourth quarter, he was booted out without incident.
Must have been some Alabama people in there.