Agencies shall not require a contractor, or subcontractor at any tier, to use FPI as a subcontractor for performance of a contract by any means, including means such as—

(a) A solicitation provision requiring a potential contractor to offer to make use of FPI supplies or services;

(b) A contract specification requiring the contractor to use specific supplies or services (or classes of supplies or services) offered by FPI; or

(c) Any contract modification directing the use of FPI supplies or services.