:* It does not fall under links to be avoided.
1 Any site that does not provide a unique resource beyond what the article would contain if it became a Featured article.
 It has many resources that are not on Wikipedia.
2 Any site that misleads the reader by use of factually inaccurate material or unverifiable research. See Reliable sources.
 All the material sites sources.
3 Links mainly intended to promote a website.
 It is not a site made to promote other websites.  I look at it, and it shows very few ads when compared to a CNN.com, and it ask for donations, just like Wikipedia.
4 Links to sites that primarily exist to sell products or services. For example, instead of linking to a commercial bookstore site, use the "ISBN" linking format, giving readers an opportunity to search a wide variety of free and non-free book sources.
 It doesn't like to sites that primarily exist to sell stuff.  It links mostly to news sites, like the Washington Post, MSNBC, and others.  It also links to sites like archive.org.
10 Links to social networking sites (such as MySpace), discussion forums or USENET.
 Were does it link to sites like this?
12 Links to open wikis, except those with a substantial history of stability and a substantial number of editors.
 Where does it link to these?
13 Sites that are only indirectly related to the article's subject: it should be a simple exercise to show how the link is directly and symmetrically related to the articles subject. This means that there is both a relation from the website to the subject of the article, and a relation from the subject of the article to the website. For example, the officially sanctioned online site of a rock band has a direct and symmetric relationship to that rock band, and thus should be linked from the rock band's Wikipedia article. An alternative site run by fans is not symmetrically related to the rock band, as the rock band has only indirect connections with that site.
As far as I can see, the site is directly related to the 9/11 attacks.  Hence the name, "Complete 911 Timeline."—