There are a huge number of hurdles to be overcome for someone to be prosecuted for killing an intruder, one of them being the likelihood of a conviction. Juries will be sympathetic to people defending their own homes, because it is so relatable.
There have to be some, extreme circumstances where it’s the correct course of action though. The threshold is, rightly, set very high for such a prosecution, but people cannot have complete carte blanche, otherwise it would be permissible to torture for weeks on end and then kill and dismember a teenage intruder you had caught in your home. No reasonable person is going to say that is acceptable, even though the youth was clearly in the wrong by being there.
I don’t know the background to this case, but I do know it’s a charging decision that won’t have been arrived at lightly. There are strong public policy reasons for people being confident of defending their homes robustly, with weapons if required, and to the death if necessary. Again, no reasonable person would argue against that. People should be free to defend their homes in a proportionate manner without fear of prosecution.
People who burgle dwellings are lowlife fucking scum and can have no complaints when people defend their territory.