Whoever holds the private key for P1 can easily calculate the private key for P2. I haven't been following your scheme but I presume that's the issuer. If I catch on correctly then the issuer could misrepresent some information about the bond, saying that the issuer public key was actually P2.
Very true, I hadn't thought of that, So yeah that underlines the point that you need to have the pubkey contained in the hash (and confirm it matches of course) to prevent this class of attack.