The author rejects unit tests because they don't help find bugs. I don't think his reasoning adds up to much, more like rationalizations for already-held beliefs.
But if you want to take the argument seriously, I would say that "finding bugs" is not the primary reason I write unit tests anyway. It's to prevent regressions, and make me feel safe that I haven't broken anything after a refactoring. If not for my unit tests, I'd be scared to change much of anything, for fear of stirring up a whole bunch of trouble that I'll have to fix later on.
But if you want to take the argument seriously, I would say that "finding bugs" is not the primary reason I write unit tests anyway. It's to prevent regressions, and make me feel safe that I haven't broken anything after a refactoring. If not for my unit tests, I'd be scared to change much of anything, for fear of stirring up a whole bunch of trouble that I'll have to fix later on.