That shouldn't happen, as you can see by checking the sim.cfg of any GSX vehicle, Swissport can only appear at those airports in the US:
PANC KATL KBOS KIAD KLGA KLRD KMIA KBNA KEWR KMCO
And, even on that one, it's not even guaranteed Swissport would always appear, because they would compete with other operators with the same score. For example, at KATL, Delta and Air Tran have the same score, which means each one have a 33% chance of appearing at any given parking.
