Nikhil's original thesis that comfort can be detrimental to productivity is right on the money. Sure, he may have been a victim of his own emotional whims, but that doesn't make his initial point incorrect. If the retort was correct, why is it then that you have such an aversion to a comfy chair at work?
It's simple. Comfort can quickly draw away focus and lead to procrastination during periods of free-time or when tasks are not entirely pressing. Certainly, one's environment can also play a role in this but comfort always comes first as far as letting one's motivation slip. And then, of course, there's the all-important factor of one's motivation itself, which needs to be taken into consideration when mulling over why some work gets done and other doesn't.
The takeaway here is that you can't discount Nikhil's argument entirely. Comfort isn't always the culprit when it comes to productivity - there are other factors at play - but it's definitely a factor worth considering. So next time you find yourself in a comfy chair with some work to do, try thinking of it as UrRong and switch seats before you fall victim to your mind's temptations!