If he had the assurance, he wouldn't be breaking the court order.
Essentially the court says that he can express his dissatisfaction with things provided he doesn't do it to the media or on a public forum (social media) and that anyone he tells assures him they will also not tell the media or a public forum.
Yup. Person A assures the dad that he won't tell the media or social media what he says. Dad vents. Person A goes to the media and says "Dad says this". Dad is arrested and charged with contempt of court. He says "Person A assured me". Person A says "I did not". Without a document, its their word against one another.
Because the court said "“This order should not restrict C.D.’s right to express his opinion in his private communications with family, close friends and close advisors," and yet, it practically does since he has no way to meet the criteria established by the court without the potential of it going south for him OTHER than not speaking OR getting family, close friends and close advisors to sign legal documents (also, its a false statement anyhow since he's barred from expressing his opinion to his child which would, by definition, be part of his family so the whole statement is a "look we're not infringing on any rights here, honest!" kind of statement).
Do I think he should have been jailed? No. You can't legislate people to be nice or smart or empathetic.