Selecting choosing and preferentially supporting people based on their faith tradition, as a proxy for individual merit, has its negatives.
For example, the "tangle of religion and work at the Los Angeles bureau", when the FBI bureau is supposed to be a secular workplace.
For another example, blacks were a sort of second-class citizen in the LDS Church until 1978; unable to join the priesthood the same way non-blacks could. Even now, black members are relatively uncommon in the US compared to the national demographics. And women may not be ordained priests in the LDS Church.
As the article mentions, "most people working for the FBI are white men." Preferential recruiting for Mormons, if not done with brains, has the secondary effect of reduced recruiting for blacks.
Preferential support for Mormons, after all, is what lead the judge to determine the FBI "made personnel decisions which favored members of their church at the expense of Hispanic class members".
Perhaps one of the unsaid factors is that Mormons are more willing to work in an organization like the FBI with a white, male-dominated hierarchical power structure, without rocking the boat? A.K.A "good cultural fit"?
Sounds like a no-brainer indeed.