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...