Is It Appropriate To Turn Political Issues Like 9-11 Into A Children's Coloring Book?

Is it appropriate to put difficult political issues into a children's coloring book?

More specifically, are graphic depictions of 9-11 appropriate for children of such a young age?

The photo below is one page from a recent children's coloring book.

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http://gawker.com/5235908/what-is-your-favorite-page-of-the-911-coloring-book?skyline=true