XKCD's WhatIf came up with a Space Oddity Music Video [http://what-if.xkcd.com/45/]?
Short version: No. Because the ISS would have existed anyway.
So to respond to your own points:
Tom Francis' PC may have cost more than $30, but he probably already had it before he started working on Gunpoint. Had he never decided to make Gunpoint, he would still have spent whatever amount of money it cost to build the PC.
His food costs will have been higher than £30, yes, but Gunpoint is something that he did in his own free time. Had he done something else with his free time, and continued with his day job, those food costs would still have come up.
The length of time spent making it: It's somewhat difficult to put a price on an hour. Especially if that hour is spent doing something that you enjoy, and that you chose to do. He quite clearly enjoyed making Gunpoint, judging by various blog posts and the trailers and, well, the game itself. Making Gunpoint was its own reward. Yes he could
have used that time to earn money, but I don't think of Dark Souls as costing me money when it forces me to redo the past hour of gaming.
The money he was paid by his employer while he was making the game... I'm not actually sure of the point you were making with this one. Yes, he will have been paid more than $30 while working on the game, but that's money going into his account, not out of it, and entirely unrelated to Gunpoint. You say he 'must' have used more than $30 of the money he earned to make Gunpoint. How do you know?
You're right that most people don't have Tom Francis' resources. They may not have a reasonable PC, or enough free time to make something like this, or sufficient background knowledge of coding to have a chance at being successful. But Tom had all those things before
deciding to make Gunpoint. Therefore they did not contribute to the cost of making Gunpoint. I'm actually curious what he would include in the $30 price mark.