It's a mistake to take an oath that winds up with you in jail.
It wants to be more of a "I'll do this but not if it means that" sort of thing, and not the sort that requires a person to defend a complicated document like the constitution. That document has a system of protection and interpretation, which is called SCOTUS.
As one notices in chat rooms everywhere, it's not the sort of document that a fat guy with an odd beard, a pick-up truck and a gun is likely to understand. Heck, even the attorneys disagree about every little word.