It was perfectly sensible and appropriate they refused her offer at first. As we later saw, they weren't at that point desperate enough to spoil a guest's vacation by having her work instead of relax. Ohana should have understood it from her own point of view as well: If a person visiting Kissuiso was forced, for example, to clean the bath themselves because no staff member had had time to do it, it would be a disaster to the inn professionally. Aside from such issues of pride, this was probably a jolly opportunity for her to experience how things work at bigger places, so it's not like she was only saving the hotel selflessly. But I do hope she at least got paid with a nice bonus!