Ugh. Can not get through to FIL that he is not able to live in independent living. What should I do?

So last week FIL with dementia in AL told us he wanted to move to a different facility because he wants better food. This week it turns out what he is really looking for is to go back to independent living. The past 10 months we have had multiple conversations of why he can’t go back to live in independent living. He’s been in AL since last May. We keep telling him that his mobility is an issue. He barely walks with a walker and at times needs help getting up from a chair. He also needs but refuses help with hygiene. He was recently told by the doctor that he has Dementia and does not accept this diagnosis. He says his “brain is as good as ever “. He is now on a crusade to prove he can live in independent living. He has recently agreed to PT and OT and says he is showering on his own (no proof). He still wears the same incontinence brief all day and leaks. He keeps complaining that he lived in independent living in Florida. We’ve told him that even Florida will not let him back into independent living. He won’t listen, FIL willingly moved near us when his wife died rather than be alone in Florida 1200 miles away. Even if she had not died, they both needed AL. They should not have been in independent living anymore. Hubby has durable POA. FIL thinks and acts as if he still calls the shots. He also asked for his checkbook “in case he needs to write a check”. I think he’s going to demand to go back to Florida to his independent living apartment. What do we say when we tell him it’s not possible to move to independent living? It doesn’t matter what state he lives in. He’s not rational. He’s going to blow up. He has never been nasty with us yet. But he has been verbally nasty to staff at the facility.-