Indeed, an opinion held by legal experts, as the title of the submission quite clearly expresses. And on the other hand there is a history of Apple refusing other government requests.
A government agency can tell people whatever it wants, if it doesn't have a legal basis then it has no authority. Unless it doesn't respect the rule of law. It might and probably will follow up its orders with force, but that's still not lawful.
What does that mean? A government agency can ask a company to do something. But unless there is legal force behind the order, it is nothing more than a request and can be ignored. In ambiguous cases the lawyers of each side will decide if they want to go to court over the matter. Eventually either the government will fold or the company will give in to the request. Until then it is a matter of opinion.
Of course the government could also exert other means to pressure the company or simply negotiate. But that's outside of the rule of law.
At least not in a logically valid way.