One reason for the determination, the official is a nationally known gay rights activist.

Via PJ Media:

A former high-ranking San Francisco government employee convicted of felony possession of child pornography will continue to receive his government pension because, according to city regulations, evidence of “moral turpitude” is required to revoke a pension yet viewing violent kiddie porn does not qualify as moral turpitude.

As reported here in the Tatler, Larry Brinkin, a prominent San Francisco Human Rights Commissioner and nationally known gay rights advocate, was arrested in 2012 for possessing and possibly distributing videos and images of babies being raped by adult men. Because of Brinkin’s “iconic” stature in the community as the person who pioneered “domestic partnership” laws nationwide, supporters at the time accused the police of framing him with false charges. [...]

But the scandal didn’t end there. A recent law defining which type of actions count as “moral turpitude” required to nullify municipal pension benefits does not include sex crimes involving children, and only refers to financial crimes:

Knox said he did not believe Brinkin’s city pension would be affected by the plea because his conviction doesn’t fall under “moral turpitude.” Under Proposition C, approved by voters in 2008, a city employee convicted of a crime involving moral turpitude – usually theft, fraud or a breach of the public trust – cannot collect employer-funded retirement benefits.

Keep reading…http://weaselzippers.us/san-francisco-of...oral-turpitude/

I am guessing that the only why to breach the moral turpitude clause anymore is to have genuine snuff porn or a copy of Guns and Ammo.

This is considered exculpatory in cases like this when it comes to San Francisco: "nationally known gay rights advocate"