I believe that it's a Court thing as the Commonwealth of Mass has decided that anything that propells anything is a "weapon." Kind of the same rationale that pepper spray is ammunition, and that expended cartridges require an FID. IIRC a kid gor in trouble a while back for shooting airsoft pellets from a disassembled pen, a la spitballs from a straw.
As for stick figures....well, that's another thing. I told my kids to ALWAYS put a rainbow in their drawings....there are never meetings about rainbows!