The American constitutional fetish does seem very strange to me as a non American. Americans (or a significant subset there of) seem to think each and every right is distinct and absolute and ignore how they interact. People are way too boxed in by the existing constitution and unwilling to consider the possibility it should be changed. That is why every argument about gun regulation hangs on parsing the second amendment instead of an open discussion of what would be best for the people/country. It is almost like the constitution is some sort of unchanging secular bible instead of a living document crafted by and for the people.
Anyhow,different countries are different. To each his own.
The document should be considered 'living' only in that it allows for it to be amended through a specific process. The Constitution was designed to put our government in a 'box', thereby leaving the citizens free to have any rights/powers not expressly forbidden in the document. Yes, there are instances where the existence of certain rights can inconvenience (or even endanger) citizens, but we believe that those are the acceptable consequences of a free society. Think of it as a backstop to help keep government from aggrandizing itself with powers it should not have (unless an amendment is passed to provide that power.)
A good example would be due process, whereby everyone gets a jury trial, even in the most obvious cases where we 'know' the suspect committed the act. The writers of the Constitution recognized that, without this due process, it would not be long before the the government would be charging citizens with bogus crimes because it 'knew' they were guilty. This also means we may have some folks who are guilty that get off because they were not accorded their rights. That sucks, but it still beats the alternative.
To better understand this 'fetish', I'd recommend reading the document in its entirety, as well as the Declaration of Independence, and some of the Federalist Papers. And, while not perfect, it established one of the longest continuously running representative forms of government in human history. Not too shabby.
With respect to this App, I rarely drink myself (maybe 2-3 times a year), but this 'request' isn't too far from telling me I can't call a friend and saying (or using Twitter to say), 'Hey, there's a checkpoint on XYZ street. Be careful.' That is not something our government should be able to stop. Sadly, my guess is that Apple will cave, especially now that the DoD is working to integrate iOS tech into the military. The Senators could come back and threaten to 'alter' those arrangements if Apple doesn't 'comply.' A sad state of affairs indeed.
Peace be with you.
