Really? The last quote seems expressly anti-rationality. Especially considering the source.
One could make an argument that, in the world of Warhammer 40K, keeping your mind barred and guarded is actually the most rational thing to do. Because if you do not, then instead of saying things like "only in death does duty end", you'll find yourself saying things like, "maim kill burn MAIM KILL BURN" and "Arrghbllgghhayargh NURGLE". Only it wouldn't be you saying those things, precisely, but a daemon that slipped into your unguarded mind and took up residence in your body.
Here's the new thread for posting quotes, with the usual rules: