Though not yet proven, wasn't a similar logic used by HR (or higher management) to justify not taking action against "star performers" for their transgressions?
Almost exactly the same, came to mind when I read that also.
I suppose there's some tipping point of "very valuable" and "not that badly behaved" where the argument is actually valid (see: all the Steve Jobs references in this thread). But at that point I guess the ethical solution is to make it very clear what new hires are in for, and pay a healthy "dealing with this person" bonus (see: Steve Jobs, again).