Let me clarify: Ker required the question's answer to earn her services in transporting the group across dimensions. However, unrelated to this, anyone crossing dimensions for the first time starting a few weeks/months after the Holocaust, anyone trying to get in or out of the Cantinaverse has to go through the white room and pass through it successfully.
Irvine was on Guy's ship at the time of transportation, and so was transported to the white room with it.
Forum A-Wing pilot of mysterious and indistinct gender. Aresener now and forever.