This, to me, is rather like questionable shoots with police. There are times when, if we weren't present, it's really hard to tell if someone has over-reacted, or not.
Now, to be very frank: we don't know if someone listening to a track of someone screaming "NO, Stop!" very loudly was playing, or if it just sounded like the regular sounds some normal people make, at reasonable volume...
but if it's the latter, I can assure you that this man is damn lucky it wasn't me, or someone like me, whose door he kicked in while his neighbor was having consensual sex. Or even just peacefully watching a porno.
It strikes me that a reasonable person, who would be reasonably armed if someone bangs on his door and then proceeds to kick it in, would be more than reasonably justified at taking aim at the madman holding a sword who has just kicked in the door of his domicile, and would then proceed to address the problem with at least two good hollow points, which might reasonably be expected to resolve the issue.
Since we weren't there, we really don't know, and we can't really call it. Yes, this man could have been acting reasonably, or he could be a social maladept who could reasonably have been Darwined out, to the good of the gene pool. We just don't know.
John