So fire dust can very clear behave very differently whenever the writer wants it to, since it can be both a highly explosive material or work like gasoline. Things that are ridiculously different in the real world. It making the nuke shouldn’t be support to anything, especially when it’s only the fuel source in the verse. It’s like say magic being able to be low 7-B in a verse supports a character being 8-C even if the explosion they do isn’t shown to be 8-C at all.