Smoke detector user manuals might vaguely allude to such a law to justify crappy engineering, but that's not the same as a citation to specific Federal, state, or municipal codes, or even an insurance underwriting code.
"The U.S. model codes and installation standards require smoke alarms and smoke detectors to be listed in accordance with the Standard for Single- and Multiple-Station Smoke Alarms, UL 217, and the Standard for Smoke Detectors for Fire Alarm Signaling Systems, UL 268."
http://osfm.fire.ca.gov/firelifesafety/pdf/Smoke%20Alarm%20T...
Why are people carrying water for this idiocy? Nothing in the document you linked has anything to do with the subject at hand. Fine, whatever, you're not supposed to be able to mute the detector in the presence of heavy smoke. But there is absolutely no prohibition against a mute feature in general.
Poor engineering on Nest's part led to a situation where a poorly-thought-out regulation came into play. Neither condition is defensible... yet look at all of the people in this thread trying to defend one or both.
(Yes, I'm moving the goalposts to a certain extent, as I was mistaken about there being no law against silencing a smoke detector in the general case.)