By saying it applied to something that specifically does not meet the very clear definition of the law? “One function of the trigger” isn’t ambiguous in any way shape or form. They are not legally machine guns under the law regardless of what they can achieve by means other than sustained full automatic fire.
It’s actually a specific thing defined under the law, and the ATF job is to interpret that statute as it applies to inventions in the marketplace.
By saying it applied to something that specifically does not meet the very clear definition of the law? “One function of the trigger” isn’t ambiguous in any way shape or form. They are not legally machine guns under the law regardless of what they can achieve by means other than sustained full automatic fire.