Please understand that the website in question provides a "Cliff's Notes" version of Objectivism suitable for a dynamic internet audience with a vanishingly short attention span. It is not a well-defended treatise, and should not be viewed as such. I find it to be a good "quickie" intro into the basic tenets of Objectivism, and philosophy in general.

I can give more/better sources if desired. Feel free to PM me.