Saw The Light,
I was under the impression that at the time the Careflight crew were winching near high voltage lines and this is what the accident was attributed to. However, your explanation does sound more plausible and is no doubt closer to the truth. This being said, I was always advised (SOP style) not to arm the cable cutter if in the vicinity of high voltage lines.
As a side note my wife worked with the Doctor that was dropped (he made a full recovery by the way). It was interesting to compare notes with him, as, I have been cut off the wire myself (Thanks Geoffro, you saved my life!) and it's not fun, it's bloody scary!