Originally Posted by
poisson
The CBP folks don't care about the alcohol percentage and in fact they don't seem to care about alcohol anyways. It's the airline and cargo folks who probably care but they aren't the ones scanning the checked bags. By the time you get to the destination airport and reach customs, the danger element of 70% alcohol being in the cargo has completely vanished.
Laws don't start and end around the "present danger" as much as they are designed to control certain behaviors as a whole. While you may never have an issue, it is illegal to carry flammable liquids on a plane.