The full-fare refundable "loophole" is legal as far as I can tell. The issue is whether TSA will alter CAPPS/SF/whatever to flag full-fare purchases, or to look for duplicate bookings under the same name originating at the same airport on the same date, or some similar set up.

The following would apply to alterations of a BP to remove SSSS or to indicate that secondary screening occured when it did not.

CODE OF FEDERAL REGULATIONS
Title 49 -- Transportation
Subtitle B -- Other Regulations Relating to Transportation
Chapter XII -- Transportation Security Admin., Dep't. of Homeland Security
Subchapter C -- Civil Aviation Security
Subpart A -- General
Part 1540 -- General Rules
§ 1540.1 Applicability of this subchapter and this part.
This subchapter and this part apply to persons engaged in aviation-related activities.

Part 1540.5 -- Terms used in this subchapter.
...
§1540.5 Sterile area means a portion of an airport defined in the airport security program that provides passengers access to boarding aircraft and to which the access generally is controlled by TSA, or by an aircraft operator under part 1544 of this chapter or a foreign air carrier under part 1546 of this chapter, through the screening of persons and property.

Subpart B -- Responsibilities of Passengers and Other Individuals and Persons
§ 1540.101 -- Applicability of this subpart.
This subpart applies to individuals and other persons.

§ 1540.103 -- Fraud and intentional falsification of records.
No person may make, or cause to be made, any of the following:

(a) Any fraudulent or intentionally false statement in any application for any security program, access medium, or identification medium, or any amendment thereto, under this subchapter.

(b) Any fraudulent or intentionally false entry in any record or report that is kept, made, or used to show compliance with this subchapter, or exercise any privileges under this subchapter.

(c) Any reproduction or alteration, for fraudulent purpose, of any report, record, security program,access medium, or identification medium issued under this subchapter.

* * *
United States Code
Title 18. Crimes and Criminal Procedure
Part I. Crimes
Chapter 47. Fraud and False Statements

47 U.S.C. § 1001
a) Except as otherwise provided in this section, whoever, in any matter within the jurisdiction of the executive, legislative, or judicial branch of the Government of the United States, knowingly and willfully--
(1) falsifies, conceals, or covers up by any trick, scheme, or device a material fact;
(2) makes any materially false, fictitious, or fraudulent statement or representation; or
(3) makes or uses any false writing or document knowing the same to contain any materially false, fictitious, or fraudulent statement or entry;

shall be fined under this title or imprisoned not more than 5 years, or both.

(anything in bold is my emphasis added)