Shared Ownership & Mortgage Interest Benefit

My son Matthew is 34 years old and was diagnosed with Aspergers when he was 18 years old.  The turning point for enabling him to live a more independent life was when he moved into his own house over 8 years ago under the Homes for Long Term Disabled (HOLD) scheme with Advance Housing.  This government sponsored scheme has helped thousands of people with disabilities move into more appropriate accommodation but is now threatened by last year's cut in Support for Mortgage Interest benefit (SMI).  My wife and I are now having to help Matthew financially to help him keep his home and this has undermined his self esteem and indpendence.  We are keeping the seriousness of the situation from Matthew as his depression will worsen if he knows his whole way of life could face sudden change.  Other than the government deciding to make special provision for the disabled, I do not know of a solution.  Is anybody else in this community in a similar position?