I certainly agree that Rochabian should indeed register himself and I also heard about this keyfile.. Apparently the owner of the key gave it up ?!?!?!?!
I don't condone this behaviour and it is wrong as the key is registered to one person.. If this person no longer needs the key s/he should delete it!
As for injecting (is that the right word) a keyfile into an iso.. I cannot see anything wrong with this as long as the ISO is NOT spread.. if it is and the keyfile becomes blacklisted then it is the users own stupid fault.