I think this may be a situation of putting the cart before the horse.
Firstly, if you own your own home but need to go into some form of residential care, assuming that social services are involved (and that's a big assumption: in a lot of areas if you're in that situation you're on your own), someone is going to have to sign a contract with the care home. There is no way that that will be social services UNLESS you or your representatives agree to a charge. If you don't agree to that charge, you'll be signing that on your own behalf, and you'll be responsible for the charges. If one wants to take advantage of the deferred payments scheme, then one's going to have to agree to the charge. It may not be fair, it may not be right, but it is what it is.
Now I think where it gets sticky is that many LA's will try to force the sale of the property, while some seem to be happy to let the deferred payments mount up.
What I'm trying to say is: if one wants residential care one will be signing something: either a contract with the care home, or an agreement with social services, because someone, sometime will have to pay that care home bill.