That blog is trolling. The blog author copied and pasted the material from the blog we are currently discussing, and replaced WebGL with Silverlight.

Silverlight is more secure than WPF, too, by the way, and has to be. For example, in WPF there is a very insecure static method that allows you to steal a bitmap of the entire screen! This was one of the first things taken out of Silverlight.

If you want to know more about Silverlight security, ask Nick Kramer who maintains the Silverlight security best practices document for Microsoft.