The chances of it being anything but suicide seem slim. He's wearing very ugly shoes, but all he had to do was take them off...no need to kill himself over it.
This method of dividing the torso is a very painful way to die. He would have felt everything as the wheels crushed his belly and the guts inside. Once he was cut in two he can't move. He has to wait for his body to bleed out to die. The aorta can spasm to stop or slow the bleeding. It could have taken 10-20 minutes of screaming pain before he took his last breath.
Yep, I've seen the videos of people cut in half and still alive, even talking with first responders. It's gruesome and grotesque. I suppose the victim could also die almost immediately from shock...if he's lucky.