I'm gonna question the validity of that on the basis of Haley actively running back towards the still-burning building.
Those rules quite clearly state being in an environment with fire, or air temperatures over 140 degrees Fahrenheit, or even lava; does at much 10 damage per minute, and even catching on fire does only 1d6 per round.
It seems clear to me: Miko went into the burning building to rescue civilians because protecting people she finds innocent is what she does; and because dealing with physical threats by crushing them into oblivion is how she normally does it, the risk of physical harm to herself doesn't bother her. What's your intent in trying to push such a flimsy rules transmogrification?