In Terry Pratchett's Equal Rites, he writes the following passage:
Esk, in fact, moved through the fair more like an arsonist moves through a hayfield or a neutron bounces through a reactor, poets notwithstanding, and a hypothetical watcher could have detected her random passage by tracing the outbreaks of hysteria and violence.
I don't understand the meaning of the phrase "poets notwithstanding" here. I've assumed it's a joke, but I'm struggling to understand the punchline. I vaguely recall The Light Fantastic having a running joke about the use of metaphors, but I don't quite see the connection here.
What is Pratchett trying to say with the phrase "poets notwithstanding" here?