Remember that the operative statement was "less protection systems as well known for Linux". Because of the nature of the Linux open source systems, there are less commercial programs and less commercial protection systems. I have not personally spent much time with Linux and, although I follow some of the news, have not researched the subject much myself.
0xf001, on the Woodmann Forum, who moderates the Linux Forum there, is very knowledgable on this subject and inquiries could be directed to him.
Regards,