It's not. Snake is simply the coolest character out of all of them.

We've got the entire months of September, October, and November to see more updates, Snake included. No point in showing off Snake too early...

I doubt we'll see Snake in an update. We have not seen him in any screenshot since the first videos. Besides, Sakurai said that all third party characters will be unlackable or hidden characters, and I'm sure he won't show the hidden characters in any update, no matter how tempting it is. But then again, since we already know Snake is in the game, there is a possibilty Sakurai will have him in an update, maybe...

New screens: http://media.wii.ign.com/media/748/748545/imgs_1.html

Give me a second, I'll find it

Snake will be in an update. I will bet money on it if you like.

EVERY other character received an update. Zero Suit Samus got hers in about the second month of updates. Meta Knight got his now, after 3 months of updates.

We have 3 very long months of updates to go...Snake will show up sooner or later.

Source: http://forums.nintendo.com/nintendo/board/message?board.id=smash&message.id=378427
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#251-260: Sakurai will eventually reveal all the secret characters (unknown if this is before or after the game’s release), and he will make Snake (and all other guest characters) into an unlockable character.
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#251-260: Sakurai in response to an email asking that everything be unlocked as a default = "Well... that is a tough question. As long as the internet exists, all secrets will be revealed quickly. Sometimes even before the game comes out, even. Secret characters are one of the fun parts of Smash. Although you don't want to find out until the very end, I guess [literally: 'after all,' so there is no doubt in this statement] I'll reveal them. Again, just like "Smash fist" [literally: 'Sumabura ken,' the name of the Japanese SSBM site?] I can't just hold these characters back. "
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It doesn't matter if Snake is unlockable...he can still get a profile on the Dojo.

I agree he can still get a profile, but why has Sakurai not shown Snake once since the trailers a year ago?
This is why I question whether he'll get a profile or not. It just seems a little strange.

I am pretty sure we have already seen unlockable characters... we simply have too many shown for none of them to be unlocked.