Could this be a possible reason? This is from a post I wrote back in July 2005,I was too lazy to type it again.
"There was a reason for the ranson note.
The perp did not want to leave,letting JR to think this could have been done by just anyone (crazy person in the area,pedophile stalking JonBenet, etc.) The ransom note was covert enough to let JR know,maybe not exactly who did it,but narrowed it down..........Exactly. Well Said imo, Eagle)
........These were all covert messages,that led JR to believe this was an "inside job". I believe the rest was "filler" to sound like a "standard" ransom note..........
IMO ... I think the person who wanted revenge for JR is a powerful, important person,who would not personally kill JonBenet,but paid off someone,who knows someone,who would.I also believe,JR has a good idea of who this person is ...and for reasons we don't know ... he's not talking.
It wasn't the money ... it wasn't JonBenet ... it was a message to John."