Depends so much on where you are coming from.
If you have had a go to discover how good you could be, and perhaps discovered only how hard it is, it is difficult to respond in any way more positive than "good luck chum", and very easy to chuckle sourly and think "he'll learn, some cheek to imply the rest of us haven't tried".
If your own experience of running is a matter of personal fitness and satisfaction, the concept of taking up the challenge to join the elite is a thrilling one - there is nothing apparently stopping him, you or me. You need feet. You need roads. You need time. You need determination. The game is open to anyone. That is really exciting...
if you haven't bruised your heart chasing the elusive goal before that is.
I spend most of my lurking time on the daily training thread. For a lot of folk there, running is infinitely more driven than any logical development of the fitness and satisfaction theme. Miles may make champions, but its the long term focus that makes the miles.
I get heaps and heaps of inspiration from my mates on dt thread. I am hugely touched that they pay attention to my efforts. Their generosity of spirit endows me with the courage to keep going. Again and again their encouragement has lifted me off the ropes and back into the ring as it were. That's inspiration. Not the story of one man whose efforts imply that others haven't really tried.
Having said all that, I side with the view that if he inspires some - well and good. There's room for him in the world, and I am happy for him to run in the limelight. It doesn't hurt me, and it shouldn't hurt anyone. Let him try.