This blanket restriction kills a use-case for UAVs in firefighting. That happens to be fire behavior observation. Having field observers watching the progress of the fire from a nearby and safe location is essential for the safety of the firefighters and anyone else who might be in the path. Using a UAV and perhaps a tethered UAV with it's extended air time, is very useful for this. Even a tethered unit could be placed 150 feet off the ground to give the observers a better view. But if the manufacturers blindly bend over for the FAA who consistently doesn't see these use-cases, then we've lost a valuable tool.
Open source will be the only way to go. One reason I won't by DJI products. But I fear that the air frame manufacturers will hard code these restrictions into the hardware.