An alliance is not something to be awarded to a country simply because it is a Western style democracy, as Georgia has become. Or because it has been a good friend, as Georgia has been, supporting the US in Iraq and providing the West with a non-Russian pipeline for oil and gas from Central Asia. An alliance is a serious commitment for the more powerful partner, potentially drawing it into the partner's disputes.Before an alliance like Nato extends its defence umbrella to any aspirant member it needs to be sure that country is stable, well-governed and unlikely to needlessly antagonise powerful neighbours, particularly a nuclear-armed one. Recent events have shown Georgia to be unreliable on that score.Events have also shown that the US is not about to intervene. To offer Nato membership as punishment of Russia would be reckless in the extreme if the most powerful partner is not prepared to come to the potential ally's defence. Signing a paper does not change the chemistry of interests, kinship and geography that causes a country to risk its citizens' lives for another.
For a postscript, I'll offer Crhymethinc's suggestion to me from earlier today. The way he sees it, anyone who wants to fight Russia in the name of democracy should do so. Recalling the fact that Americans crossed the Atlantic to enlist in the armies of Britain and France before the U.S. entered World War One, he invites Americans who feel especially belligerent toward Russia to do likewise and join the Georgian army, and otherwise leave the rest of us alone. That sounds like a good idea to me.