Apparently hunting and self protection is a bad thing and anything associated with it is considered to be a dangerous item.
Here is their no no list pertaining to any type of weapon or accessory:
Dangerous items: Items that pose health and safety concerns or that are regulated or illegal are not allowed on OfferUp. These include but are not limited to:
Firearms, no exceptions
Knives primarily used as weapons or for self-defense. Note: Cutlery, kitchen, and utility knives are generally permitted
Mace, pepper spray, bear spray, tasers, and other weapons used to subdue humans or animals
Paintball guns, BB guns, guns that fire blanks, Airsoft Guns, and all related ammunition and accessories
Sporting weapons such as bows and arrows, crossbows, and archery items
Swords, if sharpened or functional. Note: Decorative blunt swords are generally permitted
Weapon parts and accessories, including any item that attaches to a firearm, ammunition, bullets, clips, arrows, and bolts
Body armor, including Kevlar and other tactical and protective vests, except protective clothing for sporting activities
Regulated chemicals, poisons, or substances
New or used airbags sold separately from a vehicle
Hazardous materials such as:
Fireworks
Explosives
Items deemed to pose significant health or safety risks to others
Recalled items (see below)
Welcome to the 21st century boys...