The author points out that he does have some of the traits associated with psychopathy, he just sublimates them in acceptable ways (most of the time). Perhaps the best explanation is that this is a disorder of degrees, with only some outcomes being extreme enough to cause criminality, not that it doesn't exist at all?

Of course there's room for scepticism here and a lot of doubt about what the scans actually indicate, and this 'illness' has fallen out of favour due to concerns about its fuzzy definition, but the author is absolutely not claiming that the scans are meaningless or not associated with psychopathy.