This is a possible scenario, but I don't think they planned to leave the owner alive, and able to press charges for theft. Perhaps something unexpected did happen in the truck cab, and Tim refused to exit, because it seems strange that they would shoot inside of the truck, leading to blood stains, and possible bullet holes in the vehicle. I even wonder about ricochet, and the possibilty of them getting injured.
I keep going back in my mind to the purchase and use of the incinerator on a farm with no animals. IMO they planned on murder from the beginning. They came with a gun, and a plan. Like Sharlene Bosma, I find it almost impossible to comprehend that they were willing to murder someone just for a truck, but perhaps they were using drugs, and having delusions of grandeur, while being way over confidant in their abilities as master criminals. It is quite likely that DM, and maybe MS too, had already gotten away with murder more than once. I wish we still had the death penalty in Ontario, and if they are convicted, I think it should be used for human garbage like these two. I also am not in favour of a light sentence for CN if she is found to be an accomplice. She should spend several years in prison. It is highly probable that both she and MS have made some kind of deal with the Crown, in order to receive lighter sentences. Who knows, the trial may be shorter than we think, if they both testify against DM.