I don't know whether being a confessed child killer would have made his day to day life easier,given that he has already survived one vicious attack. Going down the religious avenue he has closed off after his perception of what it did to Sheila and June. Where do you start when you go back to the beginning? My initial thoughts were that Nevill and June adopted a daughter and not a son,so in those early days it wasn't necessarily the future of the farm which was foremost in their minds.
Personally I don't think the type of people who would attack a child killer in hospital would take any notice of his pleas of innocence - I am sure they have heard it all before - and everyone accuses him of being a charmer of "women" I don't think the inmates would be "taken in" by his charms.
I agree about the farm thing - NB seemed to be a very forward thinking and successful business man - I am not sure he would have been prejudiced towards the son taking over - it was the 80s and if Sheila had shown any inclination I am sure she would have been included in the family business.