I think you are right in what you are saying...
The way I see it is that in accepting the PPD claim insofar as accepting that he genuinely believed his life to be in danger, Masipa also accepts that there is no dolus to act unlawfully or to bring about unlawful consequences. He therefore didn't have the criminal intent for DE. However, since in the end his actions were unlawful, even though that hadn't been his intention, he is culpable and on that particular level the PPD claim fails.
(I think what I am trying to say is clear- apologies if it is a bit jumbled)
DE is the form of criminal intent.
The point about PDD is that you act intentionally but with lawful justification - the same as when a policeman shoots at someone.
Masipa found that there was no lawful justification, because OP had other obvious options.
What is bizarre is to claim you were acting in self defence but also to claim you didn't mean to shoot anyone.