Surely you can see that legally Masipa didn't establish lawful intent or exclude unlawful intent with that reasoning? The legal test to determine lawfulness of shooting requires much more than that, as has been discussed quite fully on this forum.
It was an ' in short ' kind of response as I can't compose lengthy explanatory posts at the moment. One of the issues -i think - with Masipa's wording of her judgement was that it wasn't clear enough at times, and that there were quite a few places where the implicit 'lawful' or ' unlawful ' needed to be stated explicitly for clarity.
The shooting itself would never have been lawful - even if a heavily armed intruder with previous convictions for violence had been behind the door. The act itself was always going to be found to be unlawful, but Masipa found that his intentions when he fired were not necessarily so