Fraternity revisited

This thing about the fraternity and the young man's death keeps hanging around in my mind. I am bothered by the events it generated, and I think I have figured out why. It's all about presumption. There's an old rhetorical doctrine that nobody thinks much about anymore, but that is very operative in our lives. It's called the "doctrine of presumption." What the doctrine says is that in nearly all situations in which we have to make a decision, you can make presumptions about the argument. In the case we know best, consider a guilty/innocent problem. The doctrine of presumption here is that, in America at least, a person is presumed innocent. This means that the "guilty" forces have to prove their case; the "innocent" forces don't have to. In other countries, the doctrine might be different: that one is guilty unless proven innocent.
Another of the cases where the doctrine might hold is in the matter of change. Traditionally, the doctrine has been that a new "ism" has to prove its case before it can replace the status quo. Conservatives like this presumption. Liberals, on the other hand, would rather, I think, prefer that the new is presumed to be better than the old.
Back to the frat question. The situation seems to me to be that the university acted on a presumption that if something bad happened, the fraternity had a hand in it. Thus the speed of the action that banned the fraternity from campus.
There is nothing inherently wrong in a presumption of guilt approach. Sometimes you just gotta pull the trigger when you're not quite sure.
In this case though, I wonder if it doesn't spring from either PR or CYA, rather than a desire for justice. But, as I've said, not all the evidence is available to me.