Yep. I could accept the getting surprised when they crashed in the door, but once he had the gun there would have been no attempt to say don't move any real cop would have started shooting.
Then you get him deciding to go after them with only one hand... why in the world would someone that had lost the use of one hand try to go get these SOBs with a shot gun, the most difficult gun anyone could possible use one handed. Hell he knew where they lived, he knew that the son took the former daughter in law to work each day... they are in the middle of nowhere, so just sit up a perch somewhere with a high powered rifle and pop the one taking her to work. Wait till other weeboys come to see if anything is wrong and pop them one by one. But for the love of god you wouldn't go in with a shotgun.
He did start the fire which caused a huge distraction/keep the clan busy. What I don’t get is why would the DIL change her mind one second after she wakes up, instead of the hours she had to think about it after the lunch(where she instead turned them in)
She had a black eye so I would guess he beat the truth out of her. Probably had someone in town tell them that she was having lunch with an older couple. Probably knew the grandparents were going to try that.