Just looking for some advice...?

My 96 year old grandma is in a lodge and insists on coming out at least 3 days a week to stay with my 60+ year old uncle. He has never been married and has no children. He only works seasonally and therefore on some week-ends is unable to be at the house with grandma. Is it unfair to ask her to stay in the lodge on the week-ends when he cannot be around? She is starting to become a little senile and frail and really should have someone around in case something happens. He says it won't work because she wants to come out on week-ends. How do I politely tell him that his nieces and nephew may not always be around to sit with her all day until he comes home. I'm just looking for some advice and trying to figure out how bad a granddaughter and niece that I am for not being willing to spend entire week-ends looking after her when there is an alternative option.