I really like the idea of doing two things at once without multitasking, as our brains don't handle multitasking that well. A very "two birds with one stone" concept.
The article is about "Startups that have bootstrapped their way to profitability", not "startups that are bootstrapping", so Github does belong on the list.
But I do agree with your Imgur suggestion, that would've been an excellent addition.
I would call a bootstrapped startup one that was entirely self-funded to begin with and had to operate under the bootstrapper mentality (cheap marketing, cutting costs, low employee count, etc).