The boat had not docked at 6 AM, so there was no reason for her to leave the room at that time to get off the ship. If she wanted beer or cigarettes, I'm guessing that is available on the ship. There's no record of her going shopping at 6 AM.
She allegedly left her room at 6 AM for a reason, even though she was not drunk, she was not feeling well, and she had not slept for 36 hours.
Why did she leave her room in the first place ... certainly not to wander around feeling unwell on a ship full of sleeping passengers. By all accounts, she was a high-functioning, normal, healthy, intelligent young woman. If she left the room at 6 AM, there must be a reasonable explanation.