It's a pithy quote, but without the context of the comment it's hard to say where Mr. Klein was going with it.
For example, in any artistic endeavor a creative person has to have their eyes open for the "happy accident" - something unanticipated and unplanned that works. The best GCA's may be open to that sort of thing, and be able to integrate it into their design. In that sense, a feature on a course might be considered Accidental by the architect, but the fact that they used it and intentionally left it might make others consider it Intentional...
More interesting, though, would be any cases that anyone can remember where, after a course has been built, something happened either with the ground or with some accident of nature that fundamentally changed a hole for the better, without the intent of the architect. Seems like that would have had to have happened somewhere, sometime.........