He doesn't want his crime to ever see the light of day.
The criminal statue of limitations for his attempted murder of her may be up, but not for a civil case brought by the family. If she ever implicated him as the reason she is in this condition it would wipe his sorry a-s out for the rest of his miserable life.
Were she to regain her words and tell the story, it would be newly discovered "evidence" and any statute of limitations would not matter. Nevertheless, I do not believe there is a statute of limitations on attempted murder in most states.
I think that there is little chance of that ever happening. And it seems that there is nothing but accusations and some doctor who believes that.
Having no access to medical records or no words of defense from the husband, I would have to make the assumption that the authorities looked into the evidence and found nothing. I can make no other assertion.
Apparently the court is satisfied as well.
So, it come down to they say he said. That is what civil courts do, is to determine weigh and likelihood of evidence. They ruled in the husbands favor.
If they are wrong, there seems to be nothing there to change their mind.
I'll admit, that courts are wrong sometimes. justice is not a perfect science and people do evil things.