Except that your plagiarism example ignores one very salient point. The government isn’t telling universities that they are required by law to investigate and enforce plagiarism rules.
I am reading the “Dear Colleague” letter right now (thanks Stephanie) and I just got to the part where it explicitly requires that universities, make a decision, and implement a consequence. I can’t think of any other infraction that a student can be accused of where the government requires a similar response. Thus, it becomes impossible to take rape out of the equation.
I am still reading the letter, so I have yet to confirm or deny the “preponderance of evidence” part.