The one you linked to is a hidden object game, so it is the theme that is the problem, not the gameplay. Is it because it is seen as historical, and therefore somehow not real, that it is acceptable to have JtR as a theme, but not Steven Wright?
Just googled Jack the Ripper game and a link came up for a game on addictinggames (where I bet loads of your kids go to play stuff). I don't think it's the same one you are talking about, but worth a mention. The description is "The “ladies of the night” go down so much easier than the men do. Take control of this murderous legend and wreak havoc on London streets." It has a Teen Caution warning i.e. it is suitable for over 13s.