Columbia College does not require a "thesis" for graduation. What the author of the article must be referring to is some time of senior paper. These are always returned to the student and are not kept by the Univeristy.
...some type of senior paper. It's early ... need some coffee.
From what I’ve read, it doesn’t even seem to have been a “senior paper” (which usually means a paper not for a single class but as a capstone to one’s studies), but rather a simple paper within a single course.
This may not be exactly what happened, but that’s what I recall from earlier discussions of this.