You wrote that the reason the park closed was because of the accident, I can fully understand that I am sure it did a bit of harm to the visitor numbers, however it was certainly not the reason of the closure, beings that the accident was in 2007, the park were cleared of any wrongdoing in 2009, and the park closed at the end of 2010!
There have been plenty (unfortunately) of Theme Park accidents around the world, even quite a few at some of the Six Flags properties, these did not affect visitor numbers, there have been incidents in the UK too which have not affected visitor numbers to the point of closure, so I am not saying that is would not have affected the visitor numbers, just merely saying that considering the timeline, it was not the reason for closure.
I'm sure there were a number of factors which caused the closure, one of them was the death of a worker which had negative press and also the declining numbers going to the theme park (which was partly caused by the death and various other reasons). I'm sure there have been other incidents in the UK and around the world but i was just stating one of the reasons that it closed.