If it hasn't been tested in Safari, they should not state that it does not work in Safari. A better message would be "We have only tested this in Chrome and Friefox on Windows, so this application might not work for you."

It is a bit like the difference between "File X does not exist", and "Could not find a file named X". Computer programs should be polite to the limit of serfdom, or they will come over as arrogant.