They cancelled it? I find that hard to believe but what do I know. Ebay exists to make money and they will literally sell anything unless it is illegal, from used panties to dog sh*t. Unless this book is selling something that is illegal they will not take it down. If they did I suspect it is because this book is telling people to break a law.
Can't list guns on EBay. Don't know where you're at but they are legal where I live.
My guess is that EBay picks and chooses. Of course they have guidelines to follow, but they can ignore them.
I'd relist the item as-is until a real person explains why they consider it "inappropriate".