Is it possible (or legally acceptable) for someone to believe their actions are lawful even when it has been entered into evidence that they have the KNOWLEDGE and training to understand such actions are indeed unlawful?
Does the law ask whether they held the belief that their actions were lawful or does the law ask whether or not they had the KNOWLEDGE of the lawful/unlawful nature of their actions?
Is the court obliged to accept the accused's claim that they "thought" or "believed" they were acting lawfully when it has been proven and entered into evidence (i.e. Sean Ren's testimony re: Oscar's firearms licensing exam) that they clearly knew and understood the law regarding the use of lethal force under those circumstances?
Why does this argument only apply in OP's case and apparently in no other similar case of people shooting through doors or roofs in similar curcumstances? That's surely the point here - OP has been treated differently from the people in those cases who, all being legal gun owners, must also have passed those same tests. Why then have those cases not been treated as murder on the basis that the owners must have known they were acting illegally in shooting at someone they can't see?