Not all that familiar with this case, but what this often means is not a ruling by the university that he didn't do it, but rather that there is insufficient evidence to proceed with further action.
IOW, it's left forever in the limbo-land of he-said/she-said rather than being conclusively proven either way.
As opposed to cases, for example, where the accused was in Peru at the time, where innocence is conclusively proven.
What very few seem willing to address is the simple fact that in those common cases where both parties agree sexual activity took place, and the only issue is whether it was consensual, there is quite simply no way to prove guilt (or innocence) beyond a reasonable doubt.
In this unfortunate situation, the legal system has cheated, and people are convicted or acquitted based essentially on which person was more convincing on the stand. IOW, who told the better story.
The problem with this, of course, is that some people are excellent liars and others are unable to tell the truth convincingly when under extreme stress.
If we actually followed our own principles of justice, it would be essentially impossible to get a conviction in a date-rape case. AFAIK, in no other type of case are convictions routinely handed down based solely on the testimony of one interested party that is directly contradicted by another interested party.
Which really ought to give males, in or out of college, good reason to reconsider the wisdom of picking up random females in bars and taking them home. But it won't.
This is why colleges and universities should not have their own courts and police.