If thread is in the wrong spot, mods please move or merge away.

So I was just at a Bernie Sanders Rally, on a college campus where the most transport we get is a regional bus and transit service or two. But event security was run by the TSA, of all people. Given that Secret Service was running the show, TSA, a sub department of DHS, makes some sense, especially given that they have the most "experience" with searching a crowds bags, and disposing of dangerous bottles of water, 50 miles from the nearest commerical airport.
But what basis is the TSA given the right, given that it's remit is transportation of all sorts, not college arena?