The site renders perfectly fine and looks quite nice on my phone. I don't know that a site needs to be "responsive" if you first design it to look good on mobile.
Fonts in general and especially in the sidebar are to tiny for me to comfortably read it on my phone.
zoom in
If you have to zoom, your mobile site is broken.
Not necessarily. But it's funny, Nielsen believes in different pages for different devices. Guess he doesn't want to follow his own advise, as per normal it seems!
If you have a "mobile site" you're doing it wrong.