It is a clear misuse of the term "fire resistance". People promoting PVC will usually talk about its 'fire performance'. What they generally mean is how it contributes to the risk of fire, i.e. Toxic products, heat output, ignitability etc. If this is the only criteria that you want to compare, then standard glass also offers an increased level of "fire performance". Something that melts between 100C and 260C is not something that is likely to ever pass the applicable 476 tests for fire doors/construction without some major modifications.
Most of the literature that can be found does give out some truthful technical info, but they do a good job of hiding some important stuff too. The PVC brigade seem to carefully avoid talking about the rate of CO production of PVC, usually talking about the production of HCl instead, sometimes to the extent of claiming that HCl production is actually a benefit due to its irritant properties and its ease of detection. PVC has a much higher rate of CO production than wood. 0.06g/g as opposed to 0.002g/g.
