Are we responsible for my brother's care when his 100 days are up?

My brother is currently in a rehab/SNF facility but has used up his 100 Medicare days. He was transferred from a local hospital on 10/11/19 after he nearly died. As a result of being on a ventilator too long, he ended up with brain damage and has lost his short-term memory. He was also previously diagnosed with bipolar disorder. The combination of the two issues limits his ability to take care of himself especially medically, makes him difficult to care for, prevents him from remembering anything from one day to the next, and he often sounds incoherent (similar to a dementia patient). He also has multiple complex and painful health issues, must take pain medications daily, and is currently scheduled for knee surgery on 2/6/2020. He ran out of his 100 Medicare days and now the facility wants to evict him rather than bill Medi-Cal. A month ago we applied for an assisted living waiver with the state but we do not know when it will be approved (takes 4 to 14 months). He cannot afford even the cheapest board and care facility on his own and we can not afford to contribute to his care nor can we take care of him in our home (his income is about $840/month). Since he was able to gain back enough of his strength to perform most of his ADLs with the use of wheelchairs, canes, and/or walkers, the facility says he can be discharged. He actually needs more care with his ADLs but he is very proud and with his mental health issues often refuses help from the aides even when he needs it. He cannot do his IADLs - like manage his pain medications, prepare his meals, do his laundry, arrange for transportation, manage his medical care, etc. because he cannot remember anything from one day to the next. Also, his thinking has become very cloudy and sometimes irrational, like that of a dementia patient. His Medi-Cal provider says they cannot pay for his care with Medi-Cal until the facility submits the appropriate paperwork but they don't want to accept Medi-Cal and don't want him to stay because of his mental health issues. I contacted the local ombudsman and he says my brother has a right to stay at the facility at least until the waiver is approved and an appropriate facility/SNF is willing/able to accept him.
Last week the SNF issued a CMS form. I signed and returned the form requesting them to bill Medi-Cal since he already is approved for that benefit. The day we received the form, I called Livanta and filed an appeal.
Livanta ruled in favor of my brother only because the facility did not send the necessary paperwork. My concern is the facility is going to try and make my brother or I responsible for the cost of his continued care rather than bill Medi-Cal. Does the form allow the facility to bill my brother or I for his care after 01/18/2020? Can any entity/agency force the SNF to file for payment by Medi-Cal to pay for his continued care?