If a bird shaped / massed object presents a serious hazard to your aircraft, then your aircraft was never safe to begin with. Don't take me wrong, I'm all for responsible drone ownership and flying, however if you are seriously worried about the ability of a 2 lb drone to take down your aircraft, you should be much more worried about the 10lb canadian goose you are just as likely to hit.
First of all, aircraft fire fighting is EXTREMELY dangerous. Whether it's a helicopter long lining a Bambi bucket, or being in a water tanker dropping water on a fire, it requires extremely skilled pilots. And this is without the distraction that a fire causes - smoke, turbulence caused by the flames (they are nothing like what you get at 30,000 feet), flying low to the ground, etc.
Most aircraft are under 500' above the ground. You need to be extremely skillful when flying this low, and you feel the flames - the rising hot air are shoving your aircraft around, so it's already hard enough keeping blue side up. Then as you release your load, your aircraft's balance shifts and you have to compensate as well as try to fly your lines Oh yeah, did I mention it was smoky so you can't always see clearly out? And there's no map accurate enough so your only protection against flying into terrain is well, the Mk. 1 Eyeball?
In fact, ti's so dangerous there's an aircraft always hanging around overhead - acting as air traffic control so they control and manage aircraft timing, spacing and noting where to attack the fire as well as keeping a general eye on everything in cas something flares up. Everyone is under control in the immediate area.
The problem with a drone is it's not under positive control - who knows where the operator may fly. It's not just damaging the aircraft, but also distracting the pilots who are just trying to keep things under control. If it lands in an engine and takes it out, that aircraft and its crew may land right in the middle of the flames (there's no where to go at 500' AGL). Or it might break through the windshield and seriously distract the pilots.
Perhaps a good way to make conditions relatable to IT workers is imagine trying to write code in the middle of a call center. You have to write your code, but phones are ringing off the hook, people are chatting loudly, and then some idiot starts banging on your keyboard.
It's already a difficult and risky working environment. Drones simply add a risk element that could turn a rescuer into a victim, and that's the last thing anyone needs. It's why SAR often suspend activity when it gets too dangerous, too - because the last thing in the world you want is to make things worse and increase the number of people needing rescue.
Oh, and a crash during a wildfire can spawn more wildfires.