I have kids, so I usually work at the library in weekends or in the middle of the night. Many things could explain Satoshis posting times - especially since we KNOW he changed time zones of his files/emails.

However I think you're on a good path. If one were to collect clues like that you could assign probabilities to each clue/location and narrow your search more and more.

If you, like you mention, cross reference special holidays with postings you might get a clue to a single country.

You could also do text analysis for special phrases, sentences or sayings that might be of local nature. I you get really lucky there might be a certain misspelled word or very unique sentence that you could search for and find other avatars posting in the same style of language.

Has anyone for instance compared the wring style of Satoshi and Gavin Andreesen or other early contributors? Being anonymous is time consuming so its not unlikely that he might have merged to a real avartar while just using "Satoshi" for the dangerous stuff.

Have others here considered that the reasoin Satoshi disappeared after Gavins CIA meeting was either:
A: They told him: Dude we know its you chill.
B: Gavin is Satoshi and realized the CIA were kinda cool/not dangerous and stopped his Satoshi activity.
C: CIA knew and threatened him to become an insider.
(D: CIA used Gavin to capture/kill Satoshi - I don't see this as plausible AT ALL.)

I know the common explanation is that Satoshi stopped all contact with Gavin after the CIA meeting, but why? He was already staying anonymous and KNEW someone like the CIA might try to read every email/post he made, so whats the difference?
Even if he felt betrayed by Gavin, why not continue talking to others?
If he felt the Bitcoin project didn't need him anymore, why at that precise time?