You really do need to understand the fact that much of our nation isn’t glued to the weekend college sports games.
Unlike Vandy, I have heard of Old Miss. I’d still be guessing if I were to pick the college it stands for.
For clarity’s sake, just list the college name if the story is about a serious crime. If it’s being reported on a sports network, then of course use the ‘Old Miss’ title. Your audience will more than likely know exactly what you’re talking about.