Somebody in another thread took an interesting guess. It's the kind of phrase you'll find in legal demand letters and lawsuit notices and Christ knows he's seen plenty of those. The phrase him feel weak so he uses it now because he wants to make others feel weak.
Damned if that doesn't seem like a legit take to me.
Showerthought: mf is mezzo-forte. ff shouldn't be fortissimo, it should be fezzo-forte.