I have heard that from SFO, Oakland and Humboldt airports a few patients have been allowed to board with declared MMJ when they have made prior arrangements with the local law enforcement.
These have been very sick patients going away from home for medical treatment or hospitalization, mostly within CA.
Exactly how or who arranged these flights, and how they got past TSA I do not know.
Here in Humboldt TSA calls on the sheriffs personnel on duty at the airport if/when they need or desire LE intervention.
Apparently, no guarantees were made about what may happen as the travelers go along their trip to other airports, or security screening.
The local LEO's did not notify any outside LEO at the traveler's destination(s).
Also I do not know if the airlines/carriers were involved or that any of the information was shared with them.