To their credit, Frisk stands and watches the sleeping pirate for a little while before eventually concluding that he's not gonna wake up on his own. They kinda have to use the toilet - human food, gross - but they don't want to do it while he's in here. And there's only the one bathroom in this place. It probably wasn't technically meant to house so many people.

It seems a little rude to wake him up...but why's he sleeping in the bathtub anyway? Eventually, they lean over and poke him lightly in the shoulder.