Isn't ANSI_NULLS set to OFF by default? So the behaviour in this article will only apply if you've explicitly set it to ON. I'd have thought that deserved more than a single-line comment right at the end!
The article says this: "The handling of NULLs as we have summarized follows the ANSI standard. However, Transact-SQL offers an extension for null processing: If the option ANSI_NULLS is set to OFF, comparisons between nulls, such as NULL = NULL, evaluate to TRUE." Quite correctly, this implies that ANSI_NULLS is ON by default, and only turned off if that's what you specify.