Not true. First, PETN and RDX were found on pieces of wreckage, which the NTSB attempted to explain away as from a dog training exercise, even though parts of the plane that had those traces were where the dogs didn't go (like, leading edges of wings), and what about the famous "red residue," that the NTSB lied under oath in court about, and which the FBI carefully removed all traces of from the seats that had it, in the reconstruction.
". First, PETN and RDX were found on pieces of wreckage"
- A fine theory, except that PETN and RDX have been used in dog training exercises for explosive detection but are not used in surface to air missiles.