Look at the details and not what you hear
In the original 23 CFR 634, high-visibility safety apparel is ANSI 107 Class 2 or 3. In the amended 23 CFR 634, in the background information, the FHWA states that the "FHWA believes that the PPE for firefighters specified in the NFPA 1971 standard is equivalent to the ANSI 107–2004 Class 2 garment." The amended rule then states that when firefighters are NOT engaged in firefighting, they must wear high-visibility safety apparel. The PPE is by FHWA definition and their own stated belief compliant.