The fault lies with the company that accepted the design and built it. He is going to walk unless the lack of maintenance is proven to have contributed to the death.
I am not sure how they got the ride built, but I know that they skipped a great deal of the design testing. They ran some of the actual ride testing in the dark to keep people from seeing what could happen on the ride. When they saw that the rafts went airborne they added the net with the support bars, which are completely out of compliance with amusement park rides.
The park covered up other injuries on the ride. They lied about maintenance on the ride. They tried to get a copy of a hospital or police report from another family about another incident on the ride, and lied to both that family and the police in order to get it.