At the risk of sounding like DiogenesLamp, I agree that the order has close to zero chance of having originated with a Federal Magistrate Judge, as I understand the position, for the reason that SwordMaker gave, namely, that it is exceedingly technical in detail, and in consideration that Federal Magistrate Judges are in fact (I agree) glorified legal office clerks.
This (to paraphrase a character in “Let’s Call Saul”) is like giving a loaded gun to a kid.
My understanding is also that the decisions of Magistrate Judges are subject to review by the full Federal District Judge in Federal criminal cases. This would distinction make some legal sense since criminal matters are significantly more weighty than civil matters if a judicial error is made.
It sounds IMHO like a legal hail mary move by the FBI to avoid a full judge to get such an order. It also seems very fishy. Is the FBI trying to railroad Apple? If the FBI is certain of itself, why go to a lesser judge instead of a full district judge (presuming that is under the control of the FBI)? Is it under the control of the FBI to determine by whom (full judge or magistate judge) the decision is made? (I have never heard of a federal Magistrate Judge until now and I do not know the answers.)
Probably a necessary requirement of "procedure." The legal system is all about proper "procedure" and you are supposed to go to the lowest level court that can potentially grant relief. You never start out at a higher court than necessary.