I assume if there was any indication of inebriation that the police could demand a test, as opposed to some FAA regulation, correct?
Since they crashed they haven't even gone through customs yet so technically the crew is not in the country legally at that exact moment so jurisdiction would fall under the INS, not the local police. I assume processing them through customs was one of the first things that was done once the emergency health issues were straightened out.
It would an interesting question as to whether the state or federal government would assert jurisdiction if any criminal charges (such as manslaughter) were to be filed. I suspect that INS would defer to the San Fran police because of their expertise but who knows...
Which is precisely why I think it would be a good idea for it to be a mandatory across the board requirement regardless of where the air crew was based. Not only would it help eliminate a factor if they crew were clean, but it would avoid the risk of dramatic scenes and headlines if the cops felt that the responsibility fell to them to make it a criminal DUI type test. That would be seen as prejudicial to the investigation, as well as all the jurisdictional headaches and likely protests from the embassy at how it would all play out in the media.
And to reiterate, I'm not implying that these guys were stoned or drunk, just that in my opinion there's no good reason for exempting foreign based crews from the mandatory drug & alcohol checking.