I took a really good look at this. There are some things that don't seem right.
They have a URL lookup tool that only deals with spam, malware, and virus issues. Ran a couple pornography URLs, including one that I fought the spam for in 1997 which resulted due to the efforts of those fighting spam back then, in the original owners of Hotmail suing the pornography site's owners, confirmed still active by Zscaler, and it gave me a 0/100 score for that one. A particularly bad site for malware will get a 100/100 score, even if two or more components go over the top but that is obviously enough. Some country codes, like .ru, .kr, and even .ca, garner points, sometimes enough to be called a serious threat due to major spam gang activity, even if the domain on that country code is totally harmless and innocent of any such activity.
And for purposes of this thread, they have a couple of freebies for anyone to use for such new threats as Facebook 'Like-jacking', shopping safety, etc., but nothing to deal with such a serious threat as pornography.
Here's the site security lookup tool, free to use.
http://zulu.zscaler.com/