A dictionary definition of explosion is "a rapid expansion in volume associated with extreme outward release of energy", that includes things like, gunpowder deflagration, aerolized gasoline burning, or even a pressurized container (like a pressure cooker) rupturing. Film burning on a metal tin as they were stored could fit this definition pretty well.
If you're defining pulse wave as a sub-sonic pressure wave, deflagarations can definitely produce those, even with relatively poor fuels (e.g. wood dust). Why do you expect nitrocellulose couldn't? Not enough gas volume?
pulse waves move at the speed of sound and are not propelled by the explosion. an air compressor tank rupturing would produce a pulse wave. pulse waves alone are not fatal to humans, though you definitely feel them and hear them.
- Why would seeing a pulse wave in nitrocellulose prove that it's an explosive (as you claim), if you're defining pulse waves as any sonic wave?
I'm having a hard time understanding your position, or your reasoning for why nitrocellulose isn't an explosive. I also still haven't been able to find any resources that corroborate what you're saying.