My one experience at this sort of thing taught me that you really need to get in the water to cut these nets. And then it works only when the whale is cooperative. In our case the sperm whale was so worn out or sick she was totally cooperative and allowed us to swim all around and underneath her cutting away the net piece by piece.
I understand the anxiety of getting in the water with a creature the size of the blue whale but IMO limited experience that is the only way to free these creatures.