This is a great little paragraph. Basically what they are saying is, that unless you actively and immediately rebut their assumptions, you fall under their authority. Example, when a cop asks you if this is your vehicle your driving without plates or license, it's up to you to immediately rebut the assumption that you are "driving" a "vehicle" and are not engaging in any commerce. You have the right to not provide them with ANYTHING unless you are being accused by a witness of an ACTUAL crime. And by anything, I especially mean a drivers license, proof of insurance, and registration! If you know your rights, then you already know that ANYTHING you say or provide them CAN and WILL be used against you in a court of equity.
"The privilege against self-incrimination is neither accorded to the
passive resistant, nor the person who is ignorant of his rights, nor to
one indifferent thereto. It is a fighting clause. Its benefits can be
retained only by sustained combat. It can not be retained by attorney or
solicitor. It is valid only when insisted upon by a belligerent
claimant in person. The one who is persuaded by honeyed words or moral
suasion to testify or produce documents rather than make a last ditch
stand, simply loses the protection. Once he testifies to part, he has
waived his right and must on cross examination or otherwise, testify as
to the whole transaction. He must refuse to answer or produce, and test
the matter in contempt proceedings, or by habeas corpus."
- US v Johnson, 76 F. Supp 538, 540 (1947).