I took the photographs on purpose not too long after I ignited the fireplace so that it did not have too much time too heat and still had some blue. It seems contradictory but this is far from being a pure Planckian Radiator thus the colour is also very much correlated to what burns, i.e. natural gas. In this case, blue is surprisingly pertaining to lower temperature, indeed, upon ignition the flames are blue for a couple of dozens of seconds.
As I was just writing, my fireplace does not really behave like a pure Blackbody so it is not really comparable. Also, conceptually the path-to-white is not related to the Planckian Locus, it is required to produce pleasing images mostly because our displays do not have enough dynamic range to form scene images properly.