I read that, but then I thought why on a match day?
Two things that spring to straight to mind here. The first is that almost by definition a serial arsonist isn't likely to be entirely careful when it comes to peoples' lives - at least one of the other fires occurred during working hours with people in the factory. Even when the fires took place with no one present, there was no doubt that dealing with them put the lives of firemen at risk.
Similarly, the story of the day tells that the gates at the back of the main stand were left unlocked - unusuallly so apparently. If it was arson, could it be that the person responible assumed that he'd left an adequate escape route. Like I say, eight serious fires happening to the businesses of one man, and him apparently netting very substantial sums as a result have to make you wonder. We'll never know the truth, but Fletcher (who wrote the book that the Guardian quotes) makes a strong case, imho.
Against that, it seems that many Bradford fans accept that it was just a terrible accident. Some parts of Fletcher's narrative
have been challenged. Like I say, the truth is that we'll never know, but it is a worrying story.