NoDressSense, sorry to hear about your father.
I have worked in hostels etc as well so might be able to give a bit more of an in depth explanation....
Accommodation is split into 4 levels, with level 1 and 2 being most hostels.
If you are excluded from one project for having a history of eg violence towards staff, arson, schedule one offences then it's quite likely none of the other level 1/2 projects will House you.
He cannot access level 1/2 hostels or council housing because of his behaviour. I'm assuming he is also not suitable for a bail hostel because of this?
So my question is, where do you expect him to be housed? Because it sounds like he has eradicated all of his options.
He would have access to detoxification and psychosocial support in prison, however it's his responsibility to engage with local drug and alcohol services once released.
The odds for recovering from addiction are not very good, even with support in place. For example for those lucky enough to get 12 months funded inpatient rehab and manage to complete it, a year after they have left 1/3 will be dead, 1/3 will have relapsed and 1/3 will remain in recovery.
I wish you all the best - sounds like a terrible situation for you and him x