I wasn't at the game so I can't speak for the LSU Greeks, but I personally find it really hard to believe that any students - Greeks or not - on a Southern campus would pass up the opportunity to watch their team play football. Usually, it's the students who can be counted on to sit through the entire game, regardless of inclement weather, how well their team is doing, etc.
I've been to
many college football games in my day, and have yet to see large crowds of Greeks leaving early. (You can normally pick them out from the rest of the students because they're dressed up in badge attire and stand out from the jeans-wearing crowd.) So I'm having trouble picturing a mass exodus after LSU's first half.
It sounds like this kid just wants something to complain about. I suggest that he concentrate more on the game than on what people are doing in the stands.
Sidenote: Concerning the kid's snide comment about inviting the Greeks who stayed to come sit in the student section: Is the Greek section actually separated from the general student section at LSU???

I've been to a lot of different campuses for games over the years, and have never noticed the Greeks being placed in a different area than the rest of the student body. All I've seen is that they tend to sit together in groups -- but not necessarily
away from other students.