Even without it, it requires only a trivial amount of extra computer processor time to retrieve the PNR from the reservation system through a name and flight number or other information. I don't think it's possible to separate it out. As long as the CRS is in the U.S., the data already reside in the US. I don't think it's possible to separate out the API data from the ability of the U.S. government to get the entirety of the PNR.
