Good old CNN. Helicopters can’t fly near that volcano not because of gas damaging rotors, but because of ash entering the gas turbine engine causing it to fail.
Well, you COULD argue the ash would damage the TURBINE rotors, not the helicopter rotors (assuming it’s a gas turbine powered helo). But that argument would require a knowledgable reporter, something quite scarce at CNN.
Also, helicopter gas turbine engines probably have an upper limit on air inlet temperature. I can see where you could hit high temperature pockets of air and gas with low oxygen that would cause the engines to either flame out or overheat.
Unlike how news reporting was done in blanco America, no expert source was named, so that was CNN's benevolent "Voice of Gawd", all nosing, never wong. Are you questioning the "Voice of Gawd"?