My gut feeling is that this has been somewhat poorly worded and definitely taken out of context.
Clearly a man does not have the right, husband or not, to have sex with a woman if she says no. That's set in stone.
The law states that people must be able to consent to sex, which is what this is about as opposed to someone having sex with a woman who has said no.
Social services claim that she is incapable of consenting, which would mean even if to her husband who doubtless knows her better than any social worker she appeared to be willing and enjoying it, he would have committed an offence.
The judge worded what he meant poorly I think, as Woof identified, and I think he is only seeking to clarify for the couple what is and isn't permissible because of her state of health, to protect them both.
I don't think he's advocating rape at all, in fact quite the reverse.