JFK JR would have been 31 years of Age. The FBI vault includes the numerous times of kidnapping attempts on his life even as a grown man.

Was the letter to Biden sent by someone impersonating JFK Jr?

https://vault.fbi.gov/John%20F.%20Kennedy%20Jr./John%20F.%20Kennedy%20Jr.%20Part%201%20of%201

Page 155, someone using the name John F Kennedy Jr wrote “Senator Biden is a traitor.”