The Constitution doesn't mention geography, that's true. That could either be because the framers intended it to apply to everyone everywhere, or because they thought it was obvious it would only apply to Americans in America.
Luckily, the Constitution is not a disembodied bit of text. We have copious context to use to evaluate the significance of the lack of geographical distinctions in the Constitution. The English legal tradition, which the Constitution is a product of, is highly territorial. English law applied to Englishmen in England. Thus, it is reasonable to conclude that American law, including the Constitution, was intended to apply to Americans in America.
Scalia's dissent in Boumediene has a good discussion of the application of Constitutional rights to non-citizens: http://www.law.cornell.edu/supct/html/06-1195.ZD1.html. I'd skip to Section II to get past the political rant.
It is obviously more nuanced than you make it seem. Do you really think it would be constitutional for the government to target a specific religion or race with drone strikes as soon as any of the targeted group were to go on vacation in e.g. the Bahamas? I don't necessarily disagree with your conclusion with regard to the current drone strikes, but I think your rational/analysis is deeply flawed and there certainly isn't a complete trashing of the constitution as soon as a citizen leaves our borders.
Luckily, the Constitution is not a disembodied bit of text. We have copious context to use to evaluate the significance of the lack of geographical distinctions in the Constitution. The English legal tradition, which the Constitution is a product of, is highly territorial. English law applied to Englishmen in England. Thus, it is reasonable to conclude that American law, including the Constitution, was intended to apply to Americans in America.
Scalia's dissent in Boumediene has a good discussion of the application of Constitutional rights to non-citizens: http://www.law.cornell.edu/supct/html/06-1195.ZD1.html. I'd skip to Section II to get past the political rant.