I was thinking that it might not be wise to use Professor Dumbledore's name, in any case. It would just put MLE on alert to look for him. And then someone might see behind his appearance.

But Sirius is the most recognisable name we've got, and he's already known to be a vocal opponent of the Protectorate. Maybe we should have something that uses his reputation. The good part of his reputation, I mean, not the other stuff.