" Documented false rape accusations are uncommon."

I think that you are looking at the situation through a very narrow lens.  The vast majority of rape allegations made never even  result in charges being filed.

Just look at the local data that has been compiled about rape allegations at the University of Oregon.   Compare that data to the number of people actually arrested for rape in all of Eugene.   There is a tremendous discrepancy.

False rape allegations are hardly "uncommon".  And there are many reasons why unscrupulous people pursue them, as mentioned in this article:

http://www.cotwa.info/p/false-rape-allegations-assault-on.html

You cannot have anything close to a fair legal system, if you take the mere allegation of a crime to imply guilt.

And the thing that concerned me most was not that this was an allegation about rape.  It was the fact that the crime was reported 10 years after the fact.   No matter what the crime, that puts the accused in a very difficult position.