“[Forensic psychologist Laurence Alison] wanted to know why, if the F.B.I.’s approach to criminal profiling was based on such simplistic psychology, it continues to have such a sterling reputation. The answer, he suspected, lay in the way the profiles were written, and, sure enough, when he broke down [a particular] analysis, sentence by sentence, he found that it was so full of unverifiable and contradictory and ambiguous language that it could support virtually any interpretation. Astrologers and psychics have known these tricks for years.”
There is no mention of the very basic fact that a criminal profile is simply a tool that investigators can use if they have nothing else to work with. It's really just an educated guess based upon knowledge of who committed such crimes in the past (e.g., a married person killed at home is most often killed by the spouse) and upon behavioral psychology that can be implied from details of the crime (e.g., mail fraud isn't typically committed by illiterate short order cooks). If you have nothing else to work with, you need to start somewhere. So, you start by checking out the people who fit the profile.
It's also important to understand that if the investigators find a "person of interest" or "suspect," they do NOT change the profile, even if the profile doesn't match the "person of interest" or "suspect" in any way whatsoever. In the anthrax investigation, even if the FBI knows exactly who sent the letters, they cannot change the profile to match that person. A profile is only of value when you have nothing else to work with. When you have something else to work with, the profile no longer has any value until or unless that "something else" turns out to be totally wrong or worthless.
And the FBI cannot withdraw a profile even if they know who did it but cannot yet make an arrest, because (1) if they cannot yet make an arrest, the investigation is not yet completed, and (2) they would have to explain why they withdrew the profile.