Good and so he should be IMO plus I do honestly hope beyond hope that this poor man does not get charged and for what I can see you could be prosecuted if, for example, you: carry on attacking the intruder even if you’re no longer in danger, pre-plan a trap for someone - rather than involve the police by all accounts this seems not to apply here as he contacted the police and I don't suppose for one minute he carried on attacking this man nor tried to set out to trap them as I'm sure I read that the man who died that his partner in this crime tried to help him before fleeing the scene.
I know if I was on the jury there is no way I would send down a 78 year old man for defending his beloved wife and property.
https://www.gov.uk/reasonable-force-against-intruders