I don't thin it is. When two people who are eligible for it share the same accommodation they each only get half of the allowance. So it's not a fixed sum that is paid to everyone.
The department that pays it would probably argue that if someone is in residential care they don't need it.
Residents in a care home are paid the allowance at a reduced rate - UNLESS they are in receipt of Pension credit or income-based Jobseeker's Allowance, in which case they are ineligible.
Funding by social services means it is likely that they are in receipt of one of these benefits.