I respectfully disagree. I think it adds to the art of it for him to not come out and tell his followers exactly what it means. 'Time' is more about the emotion of the comic than a rational explanation, or a joke (like 'nerd sniping').

Exactly like nerd sniping. It's a self-selecting filter. If you don't like it or don't get it, but still come back to read more, guess there must be something for you somehow. But the target are the nerds that get sniped, not those who get frustrated because there's a lack of information.

I think. :)

Generally part of what makes something good art is the ambiguitiy around interpretation allowing space for the viewer to add their own meaning and interpretation. As a result he's better off saying very little and allowing us space to engage, condemn, question and critique.

There's also a wiki: http://xkcd-time.wikia.com/wiki/XKCD_Time_Wiki

Isn't that what explainxkcd.com is for?

Ah, thanks! This is more what I meant -- not a revelation of the artist's interpretation, but rather a technical explanation of the scripting he used and a post of all the content in its entirety.