That is the way it is with the hospice facility I'm associated with as well. Our facility only has 10 beds, they cannot take every hospice patient as soon as they are placed on hospice (going under hospice *care* is 6month or less to live). They will occasionally take a pt. for longer if there is extenuating circumstances and they have enough beds.
A question you may want to ask the hospice nurse is if you FIL is 'actively dying'. That is a term that they may use to distinguish between someone who is terminal and someone whose death is immanent. Usually someone who is actively dying has about 24hours. But, that said, I've had patients go for nearly a week that way, which is very sad, actually.