This thing and this guy sounds bizzarre! Why would China want payment in a currency that isn't real?
I'd put him on ignore if I were you. By the way, as someone else pointed out, Canada's debt to GDP is lower than US's, but US's isn't much different than Germany, France, etc. It should be dealt with, but isn't a reason to think the US treasury will torch the US$.
I say... PHOOEY! (with a nod to my Econ Prof)