To be honest thats what I thought as well.
It just seems strange to me that TP's don't seem to have QRH page for tail pipe fire yet jets do.
We can get the fuel pooling with the fixed shaft ones if you turn and pull and then spin the props you can get a 30ft after burner effect coming out the back with a huge whoosh. Which can alarm the ground crew.
The only burnable stuff up there that I could think of was the bearing oil which we tend not to have as its a sealed system that very rarely needs topping up and when its does its usually because its coming out the gear box.