I actually agree with him on the thickness, especially since I'd put the phone in a case which would add even more girth. It makes it less pocketable, and more importantly less easy to handle. My thumb can't easily reach all the way across the screen on my current, similarly sized and thinner phone already and the added few millimetres from the case do make it noticeably worse.
It's not the major thing that's keeping me away from the Fairphone (I'm just not the target demographic), but certainly isn't a point in it's favour.