I'll have to take a closer look at the hub to find out what is used as seal, but I wouldn't be surprised if it is something inferior compared to say XT or XTR. It doesn't have to be superb sealed, as the philosophy of the Grease Guard design is you easily regularly service the bearings with the Goose Grease gun. The grease will travel through a circuit, through the bearings and presses old grease and also dirt out.
A XT or XTR part you do not take in pieces every couple of weeks, so what is inside has to stay in and what is outside has to stay out.