Is there any material evidence the grandfather was attacked and/or punched?
With eyewitness testimony, none is needed. That isn't to say that there isn't any, because none of the news stories (and I've taken the trouble to look at all the ones that Google turned up, including the duplicates).
So stop spinning fantasies based on stuff you pull out of your ass. Which, as near as I can tell, is your standard SOP on EVERY self defense thread I've ever seen you post on.
I grew up in South Louisiana, surrounded by Cajuns, and married one. They CAN be VERY hot-tempered. It is far more likely, given the people involved, that the story went down exactly as reported, than the scenario you and the other two keep trying to foist off.