Air plane's salt water won't affect fire fighters on the ground who can still use fresh water with

their equipments. So, the first issue from your link is non-existent in thus case. The 2nd issue is environmental concern. I would say we need further investigation on long term effect of salt water. Nature is pretty resilient. Also, it worth using salt water if the wild fire is at very beginning stage, but the wind speed is at 60 mile. The jet- powered airplane, even with salt water, is the most effective in this situation to control fire.