I agree with John, its definitely not an FFCC situation. Normal PA/PB applies. Which is why you have to be very careful about handing over the SWU if the second segment hasn't cleared, particularly if the second segment is the important one. I once voluntarily downgraded SIN-HKG because my HKG-SFO hadn't yet cleared and I didn't want to waste a SWU on a 3hr flight. Of course everything worked out, as HKG-SFO cleared at the gate. And as John points out, if they do collect the SWU for the first segment, make sure that they put a note in the PNR that includes the certificate number of the SWU they pulled.