The Establishment doesn't like convicted criminals maintaining innocence. It unsettles the prison guards for one thing. The opportune thing to do is keep them in jail for a number of years, then release, as happened with George. Same with David Bain. There must be an insufficient groundswell of opinion heretofore in favour of Jeremy Bamber.
From experience it doesn't really effect prison guards providing the prisoner tows the line and gets on with the regime.
If anything the system accepts the court verdict. The prisoner in a sense cuts their own nose to spite their face. It used to be called in the old days for lifers IDOM. ( In denial of murder )You cant attend rehabilitation courses if you are not admitting your crime. You ultimately also end up serving well over your recommendation tariff in most cases.
In regards to Jeremy Bamber this applies to him. Even though he is life without parole. I doubt he has undertaken any serious offender management work. In his eyes it would be a tantamount to admitting gulit. Primarily I believe he just attends workshops