Clarification on 393.84 - Flooring

Clarification on a violation for floors on trailers or flat bed straight trucks that have unnecessary holes or oil permeation. § 393.84 Floors. The flooring in all motor vehicles shall be substantially constructed, free of unnecessary holes and openings, and shall be maintained so as to minimize the entrance of fumes, exhaust gases, or fire. Floors shall not be permeated with oil or other substances likely to cause injury to persons using the floor as a traction surface. [53 FR 49401, Dec. 7, 1988] 390.5T Motor vehicle means any vehicle, machine, tractor, trailer, or semitrailer propelled or drawn by mechanical power and used upon the highways in the transportation of passengers or property, or any combination thereof determined by the Federal Motor Carrier Safety Administration, but does not include any vehicle, locomotive, or car operated exclusively on a rail or rails, or a trolley bus operated by electric power derived from a fixed overhead wire, furnishing local passenger transportation similar to street-railway service.

This typically applies to the cab, however, does this section apply to a trailer floor when the hole is sufficient in size to allow cargo to fall through. Would this apply when the trailer is empty or loaded with cargo that would not be capable of falling through the existing hole? Would a trailer intentionally permeated with oil by the carrier, with the intendent of preserving the cargo (lumber for example) be in violation of this regulation?

Clarification due to definition of Motor Vehicle showing trailers apply. Is this a cab only violation or does this apply to all motor vehicles