You're absolutely right that there are reasons to believe this might not stand up on appeal. However, the reasoning from Smith is hugely problematic with the ad

You're absolutely right that there are reasons to believe this might not stand up on appeal. However, the reasoning from Smith is hugely problematic with the advent of the cloud. Smith is based on what's called third-party doctrine: basically that the Fourth Amendment applies to your stuff that's in your possession. If you give your stuff to someone else, they don't have a Fourth Amendment right to it, and the government can take it without a warrant. Before the digital age, it was unusual to entrust sensitive private information to third parties. Most of what we had was kept on paper. Now, people put huge amounts of information in the hands of third parties, often without really realizing it. Extending third-party doctrine to all digital information would decimate online privacy. This is where the future of Fourth Amendment jurisprudence is headed, and how the courts decide will have huge ramifications for the future of privacy. So again, you're right that there's significant precedent that must be overcome, but it's by no means a done deal. Even some of the conservative Justices in the recent Fourth Amendment cases seem pretty concerned.