Kylo Ren wants to interrogate the prisoner but can barely get his shoulders through the door, and even when he does, his ability to intimidate is severely limited by the fact he keeps hitting his head on the low ceiling.
Rey does not laugh.
Much.
He comes up with the flimsy excuse that he needs the largest guest suite for a proper interrogation and they are not to be disturbed.
The staff on board have enough sense not to mention that his parents stayed there on their honeymoon years ago
