This is not a good comparison. While I agree with you that a project like SnooFS is using other people resources in a bad way, projects like this are more of a proof-of-concept than anything else. I don't believe people would actually trust their files in a manner like this.
On the other hand, whereas GitHub issues are not intended for external blogs comments, it is already used like this and for blogs hosted on GitHub Pages. This is just an automation tool. If GitHub sees a problem with this in the future they can always change their terms of use (and that's why anyone should only use a system like this for ephemeral stuff).
I think this is really awesome. I know I can use ES5 and I don't even have to worry about old browsers because my app requires the latest to work, but I think this is more a preference thing.
Hell, I could even use JQuery for a lot of this stuff, but I really like ruby standard library and it's cleaness.
On the other hand, whereas GitHub issues are not intended for external blogs comments, it is already used like this and for blogs hosted on GitHub Pages. This is just an automation tool. If GitHub sees a problem with this in the future they can always change their terms of use (and that's why anyone should only use a system like this for ephemeral stuff).