The quotes are what other people have said. Jokes need to have a punchline and evoke a humour response in the audience; the references to base-1 in the ancestor comments do neither, so describing them as a 'joke' is inaccurate (hence the quotes to mark it as verbatim).
I certainly agree that overuse of quotes makes a comment pretentious!
Maybe you're not the intended audience then? Personally it got a smile out of me, and I do find some xkcd comics funny. If you don't, that's fine, but it doesn't make them not jokes.
